bluuebunny/crossref_metadata_2025 huggingface dataset:
Fe3+‐chelates mediate the oxidative modulation of cyanobacterial and chloroplast enzymes
Authors: Udvardy János , Borbély György , Juhász András , Farkas Gábor L.
Published: July 2002

Fe3+‐EDTA and the Fe3+ complexes of naturally occurring compounds (ATP, ADP, GTP, oxalate, pyridoxal 5'‐phosphate, Pi, PPi) mediated the oxidative modulation of several, partially purified cyanobacterial and chloroplast enzymes. Cyanobacterial glucose‐6‐phosphate dehydrogenase deactivated by treatment with dithiothreitol + thioredoxin was reactivated in the presence of Fe3+‐chelates under aerobic conditions. Cyanobacterial fructose‐1,6‐bisphosphatase, spinach leaf NADP‐glyceraldehyde‐3‐phosphate dehydrogenase and NADP‐malate dehydrogenase activated by incubation with dithiothreitol + thioredoxin were deactivated in the presence of Fe3+‐chelates under aerobic conditions. Cyanobacterial isocitrate dehydrogenase and cyanophage AS‐1‐induced site‐specific endonuclease, enzymes known to be devoid of redox properties, were not affected by the Fe3+ complexes. The possible role of iron‐chelates in enzyme modulation is discussed.
The nucleotide sequence of chloroplast 4.5 S rRNA from Mnium rugicum (Bryophyta) : mosses also possess this type of RNA
Authors: Troitsky A.V. , Bobrova V.K. , Ponomarev A.G. , Antonov A.S.
Published: July 2002

The complete nucleotide sequence of chloroplast 4.5 S rRNA from the moss Mnium rugicum was determined to be OHUAAGGUGACGGCAAGACUAGCCGUUUAUCAUCACGAUAGGUGCCAAGUGGAAGUGCAGUAAUGUAUGCAGCUGAGGCAUCCUAACAGACCGAGAGAUUUAAACOH. The sequence differs from that of a fern Dryopteris acuminata and of angiosperms 4.5 S rRNA by 8 and 9–14%, respectively. The strong conservation of 4.5 S rRNA in the course of evolution ensures its use for reconstruction of the phylogenetic relations between the higher taxa of plants.
Bending of smooth muscle myosin rod
Authors: Cross R.A.
Published: July 2002

Electron microscopy of mammalian smooth muscle myosin rods showed them to be 153 ± 7nm (SD) long, and to bend sharply (> 90°) but infrequently, and pH independently (range 6.5–9.5), at a single site 45 ± 4 nm from one end of the molecule. Light meromyosin (LMM) preparations were 99 ± 10 nm long, and showed no bends. Intrinsic viscosity vs temperature plots for rods and LMM indicated that neither fragment changed in flexibility in the range 4–40° C. Peptide mapping in the presence and absence of SDS established that the proteolytic susceptibility of the hinge at the N terminus of LMM reflects the presence of locally different structure, and not simply a clustering of susceptible residues. The isolated smooth muscle myosin rod thus contains only a single hinge, having significant stiffness, and lacks the second bend seen under certain conditions in the intact molecule.
Isolation of a calcium‐binding protein from an oxygen‐evolving photosystem II preparation
Authors: Sparrow Raymond W. , England Reginald R.
Published: July 2002

Heat treatment of a highly active photosystem II preparation (600 μmol O2. mg Chl−1.h−1) caused the release of several polypeptides. One of the polypeptides was found to bind to a fluphenazine‐Sepharose affinity column in a calcium‐dependent manner. The purified polypeptide was able to stimulate calmodulindepleted 3',5'‐cyclic nucleotide phosphodiesterase, indicating a possible similarity with calmodulin.
Solubilized monomeric sarcoplasmic reticulum Ca pump protein
Authors: Martin Dwight W. , Tanford Charles
Published: July 2002

Phosphorylation (by inorganic phosphate) of sarcoplasmic reticulum Ca pump protein has been studied in a detergent solution in which the protein has been previously shown to exist as a monomer. The course of the reaction is qualitatively similar to that observed for membrane‐bound (possibly oligomeric) protein. In particular, the results indicate that alternation between the two principal conformational states of the Ca pump protein persists in the monomeric state, which suggests that the machinery for coupling of ATP hydrolysis to Ca2+ transport is intact. There are quantitative differences between monomeric and membrane‐bound protein with respect to phosphorylation, but they are not necessarily related to the state of association.
Sugar moiety of cardiac glycosides is essential for the inhibitory action on the palytoxin‐induced K+ release from red blood cells
Authors: Ozaki Hiroshi , Nagase Hiromi , Urakawa Norimoto
Published: July 2002

Palytoxin (PTX), a highly toxic and sugar‐containing substance isolated from Palythoa tuberculosa, caused K+ release from rabbit red blood cells. Cardiac glycosides, such as ouabain, convallatoxin, cymarin, digoxin and digitoxin, inhibited the PTX‐induced K+ release. Their corresponding aglycones did not inhibit the K+ release, but antagonized the inhibitory effect of the glycosides. All these cardiotonic steroids equally inhibited the activity of (Na+ + K+‐ATPase prepared from hog cerebral cortex. These results suggest that the sugar moiety of the cardiac glycosides is important for the inhibitory effect on the K+ release induced by PTX and that the inhibition is not related to their inhibitory potency on the (Na+ + K+)‐ATPase activity.
Nucleotide sequence of the lspA gene, the structural gene for lipoprotein signal peptidase of Escherichia coli
Authors: Yu Fujio , Yamada Hisami , Daishima Kyoko , Mizushima Shoji
Published: July 2002

The nucleotide sequence of the lspA gene coding for lipoprotein signal peptidase of Escherichia coli was determined and the amino acid sequence of the peptidase was deduced from it. The molecular mass and amino acid composition of the predicted lipoprotein signal peptidase were consistent with those of the signal peptidase purified from cells harboring the lspA gene‐carrying plasmid. The peptidase most probably has no cleavable signal peptide. The lspA gene was preceded by the ileS gene coding for isoleucylt RNA synthetase and the tandem termination codons of the ileS gene overlapped with the initiation codon of the lspA gene.
Effects of 3,5,3'‐triiodothyronine on collagen synthesis by cultured human skin fibroblasts
Authors: de Rycker C. , Vandalem J.-L. , Hennen G.
Published: July 2002

Addition of 3,5,3'‐triiodothyrinine (T3) (10−9‐10−7 M) to the media of cultured skin flbroblasts was shown to decrease the amount of newly synthesized soluble proteins, including collagen. Polyacrylamide gel electrophoresis of newly synthesized collagen demonstrated that addition of the hormone did not affect the processing of the molecule.
Rate and duration of net glycogen synthesis following glucose administration to fasted human leukocytes
Authors: Plesner Liselotte
Published: July 2002

When glucose was added to fasted human leukocytes in a final concentration of 0.5–5 mM there was a phase of glycogen synthesis followed by a phase of glycogen breakdown. The duration of the phase of net glycogen synthesis increased with increasing concentrations of glucose applied, but the net rate of glycogen synthesis was inversely related to this figure and decreased from approx. 7 cells per min at 0.5 mM glucose to an average of 4 cells per min at 5 mM glucose.
Aldosterone secretion, measurements of membrane potential and intracellular potassium activity in the isolated adrenal zone glomerulosa
Authors: Wiederholt Michael , Hampel Jürgen , Belkien Lutz , Oelkers Wolfgang
Published: July 2002

Aldosterone secretion
Membrane potential
Intracellular potassium activity
Adrenal zona glomerulosa
Changes in diet
Involvement of protein HMG1 in DNA replication
Authors: Alexandrova Evdokia A. , Marekov Lyuben N. , Beltchev Beltcho G.
Published: July 2002

Antibodies against HMG1 inhibit the incorporation of [3H]thymidine in Ehrlich ascites cell nuclei. By the use of specific inhibitors it is shown that HMG1 is needed for the action of the replicative DNA polymerase and not for the reparative one. This is supported by the fact that the addition of exogenous HMG1 to the nuclei enhances the replication process.
Effect of ethionine on the in vitro synthesis and degradation of mitochondrial translation products in yeast
Authors: Téllez Rowena , Jacob Germaine , Basilio Carlos , George-Nascimento Carlos
Published: July 2002

The effect of ethionine, an amino acid analog of methionine, has been studied in Saccharomyces cerevisiae in relation to cell growth, oxygen consumption, in vitro protein synthesis of mitochondrial translation products (MTPs) and the degradation of those mitoribosomally made proteins by an ATP‐dependent process present within the organelle. Ethionine was found to increase the generation time of those cells already committed to cell division and to abolish the initiation of new cell cycles. Oxygen consumption of cultures grown in the presence of the analog was drastically reduced. Ethionine was also found to impair the incorporation of methionine and leucine into mitochondrial translation products, however the synthesis of proteins was not totally blocked and, apparently, mitochondria utilized ethionine as a precursor amino acid. MTPs synthesized by isolated mitochondria in the presence of ethionine were rapidly degraded inside the organelle at a faster rate compared with the normal proteins synthesized under identical conditions in the mitochondria. It is also shown that these in vitro synthesized proteins are degraded by an ATP‐stimulated proteolytic system, as has been previously established.
Cholesteryl ester transfer protein
Authors: Ierides Michael , Dousset Nicole , Potier Michel , Manent Jeanine , Carton Michel , Douste-Blazy Louis
Published: July 2002

Radiation inactivation was used to determine the functional M
r of cholesteryl ester transfer protein (CETP) in rabbit plasma from control and irradiated animals. This technique reveals the size of the functional unit required to carry out the transfer function. The functional M
r was calculated to be 70000 ± 3000 (mean ± SD) for both control and irradiated rabbits. This result is in. accordance with the M
r obtained by a completely different method, namely SDS‐polyacrylamide gel electrophoresis of a partially purified (110‐fold) rabbit CETP. The pI of this CETP was found by isoelectric focusing to be equal to 5.95. The results suggest that the functional unit of this enzyme is the monomer.
Threshold dependence of bacterial growth on the protonmotive force
Authors: Taylor M.A. , Jackson J.B.
Published: July 2002

The specific growth rate of phototrophic cultures of Rhodopseudomonas capsulata has a threshold dependence on the cytoplasmic membrane potential the major contributor to the protonmotive force. There is a strong correlation between the dependence of the membrane ionic current, the rate of ATP synthesis and the specific growth rate on the value of the cytoplasmic membrane potential.
Reconstituted high density lipoprotein behaviour is modified by the nature of the lipid vesicle
Authors: Jones Sheelagh M.A. , Rogers M.Perenna
Published: July 2002

Apo HDL is a more potent inhibitor of lipoprotein lipase than native HDL. HDL reconstituted from apo HDL and vesicles made from either HDL total lipids or HDL phospholipids inhibits lipoprotein lipase in the same manner as native HDL. HDL reconstituted from apo HDL and vesicles made from phosphatidylcholine and sphingomyelin still behaves like apo HDL.
Immunological properties of the dimeric and tetrameric hemoglobins from the mollusc Scapharca inaequivalvis
Authors: Verzili Daniela , Citro Gennaro , Ascoli Franca , Chiancone Emilia
Published: July 2002

The dimeric and tetrameric hemoglobins from the bivalve mollusc Scapharca inaequivalvis produce highly specific antibodies in rabbits. No antigenic cross‐reactivity between the two hemoglobins has been observed despite the presence of highly conserved regions, i.e., the E and F helices, in the dimer and in the α‐chain of the tetramer. These results may be explained on the basis of the unusual assembly of S. inaequivalvis hemoglobins, in which the E and F helices are not exposed to solvent as in vertebrate hemoglobins, but form a crucial intersubunit contact. The specific antibodies only slightly affect the oxygen binding properties of the respective antigen.
Convenient modification of the method for oligonucleotide‐directed in vitro mutagenesis of cloned DNA
Authors: Efimov V.A. , Mirskikh O.V. , Chakhmakhcheva O.G. , Ovchinnikov Yu.A.
Published: July 2002

A new modification of the oligonucleotide‐mediated mutagenesis technique has been developed. The proposed methodology has been used to produce specific base changes in the double‐stranded plasmid DNA. For this purpose, special cloning vectors have been constructed using the synthetic oligodeoxyribonucleotides. The developed method allows the production of mutant DNA from those of the wild‐type with a yield of 10–20%.
Tightly bound nucleotides affect phosphate binding to mitochondrial F1‐ATPase
Authors: Kozlov I.A. , Vulfson E.N.
Published: July 2002

The interaction of inorganic phosphate with native and nucleotide‐depleted F1‐ATPase was studied. F1‐ATPase depleted of tightly bound nucleotides loses the ability to bind inorganic phosphate. The addition of ATP, ADP, GTP and GDP but not AMP, restores the phosphate binding. The nucleotides affecting the phosphate binding to F1‐ATPase are located at the catalytic (exchangeable) site of the enzyme. The phosphate is thought to bind to the same catalytic site where the nucleotide is already bound. It is thought that ADP is the first substrate to bind to F1‐ATPase in the ATP synthesis reaction.
Calcium ionophore A23187 induction of spermidine/spermine N1‐acetyltransferase activity in bovine lymphocytes
Authors: Matsui-Yuasa Isao , Otani Shuzo , Morisawa Seiji
Published: July 2002

The divalent cation ionophore A23187 increased the activity in bovine lymphocytes of spemidine/spermine N
1‐acetyltransferase, a rate‐limiting enzyme in polyamine biodegradation. The enzyme was induced in a dose‐ and time‐dependent manner. Induction was suppressed by indomethacin, but not by trifluoperazine (TFP), N‐(6‐aminohexyl)‐5‐chloro‐1‐naphthalenesulfonamide (W‐7) or palmitoylcarnitine. These results suggest that the activation of phospholipase A2 involves the induction of spermidine/spermine N
1‐acetyltransferase. Omithine decarboxylase, a rate‐limiting enzyme in polyamine biosynthesis, was not suppressed by indomethacin but was by TFP and W‐7. The molecular mechanism of the induction of spermidine/spermine N
1‐acetyltransferase and ornithine decarboxylase may be different.
Modification of the amino acid acceptor stem of E. coli tRNAfMet by ligation of chemically synthesized ribooligonucleotides
Authors: Doi Takefumi , Morioka Hiroshi , Matsugi Jitsuhiro , Ohtsuka Eiko , Ikehara Mono
Published: July 2002

The single‐stranged region of the amino acid acceptor stem corresponding to the 3'‐end of E. coli tRNAMet
f was replaced by ligation of chemically synthesized ribooligonucleotides, in order to change the length of the single‐stranded CCA terminus. The chemically synthesized ribooligomers, CCA, ACCA, AACCA and CAACCA, were ligated to nuclease‐treated E. coli tRNAMet
f, which lacked the ACCA sequence at the 3'‐end. The methionine acceptor activities of these modified tRNAs were examined using E. coli methionyl‐tRNA synthetase. Ligation of the chemically synthesized pentamer (AACCA) to the acceptor terminus restored the methionine acceptor activity, whereas ligation of the hexamer (CAACCA) or trimer (CCA) to the acceptor terminus did not Modification of the acceptor terminus had no effect on the formylation of accepted methionine.
Introns, protein syntheses and aging
Authors: Picard-Bennoun Marguerite
Published: July 2002

In the fungus Podospora, a correlation has recently been established between the presence of circular DNA molecules arising from the mitochondrial genome (SEN‐DNAs) and the senescence syndrome. Here, I propose a hypothesis which accounts for the initial event which leads to the first SEN‐DNA. A molecule in the most frequent situation where the SEN‐DNA is an intron which might code for a maturase. This hypothesis is based upon several observations made either in Podospora or in the yeast S. cerevisiae. It assumes that mitochondrially synthesized maturases are unspecific nucleases able to work at the level of RNA and DNA molecules. Their specificity for RNA splicing instead of DNA is given by cytoplasmic proteins. Therefore, if the balance between cytoplasmic and mitochondrial protein syntheses is disturbed in favour of the mitochondrial compartment, the maturase would be accumulated and allowed to splice introns from DNA instead of RNA molecules. This hypothesis can account for aging of higher eucaryotic cells by postulating analogous processes in their nuclear compartment.
Optical properties and structure of tetrapyrroles
Authors: Sund Horst , Blauer Gideon
Published: July 2002

Many basic life processes such as oxygen transport, electron transport, photosynthesis and plant development, are mediated by tetrapyrroles. It has long been recognized that optical and other physicochemical properties of tetrapyrroles are highly important not only for characterization of the various relevant systems but also to provide a key role in the understanding of their structural and functional aspects. The symposium described below was devoted mainly to recent advances in the optical and molecular properties of biologically important systems, involving both cyclic and open‐chain tetrapyrroles. The topics presented and discussed ranged from physics and chemistry to plant biology and medicine. This interdisciplinary character of the meeting conforms with previous symposia also held in Konstanz: Protein‐Ligand Interactions (1974) and Transport by Proteins (1978) [see FEBS Lett. (1975) 54, 1‐4, and FEBS Lett. (1979) 103, 1‐4]. In order to stimulate exchange of ideas, new experimental approaches and techniques, emphasis was placed on the discussions following each presentation, reports of which are also included in the book published. Preprints of the papers presented were distributed some time prior to the symposium. The symposium was mainly supported by the Stiftung Volkswagenwerk and the University of Konstanz. The meeting was based on 29 invited lectures which were divided into four sections.
Mammalian ribonucleases
Authors: Beintema Jaap J.
Published: July 2002

Parts of the amino acid sequences of horse and dromedary pancreatic ribonuclease were reinvestigated. The sequence of residues 21–25 in horse ribonuclease is Ser‐Asn‐Pro‐Thr‐Tyr or Ser‐Asn‐Ser‐Thr‐Tyr. The asparagine in the latter sequence is glycosylated. Horse ribonuclease possesses four additional amino acid residues at the C‐terminus, like a number of other ribonucleases. Position 39 in horse and dromedary ribonuclease is not deleted but is occupied by tryptophan.
Nucleotide sequences of chloroplast 4.5 S ribosomal RNA from a leafy liverwort, Jungermannia subulata, and a thalloid liverwort, Marchantia polymorpha
Authors: Yamano Yoshiaki , Kohchi Takayuki , Fukuzawa Hideya , Ohyama Kanji , Komano Tohru
Published: July 2002

We found 4.5 S rRNAs in chloroplasts from a leafy liverwort, Jungermannia subulata, as well as a thalloid liverwort, Marchantia
polymorpha, and determined their complete nucleotide sequences. That from J. subulata was 100 nucleotides long and that from M. polymorpha was 103. They were strongly homologous with those from higher plants, a fern, Dryopteris acuminata, and a moss, Mnium rugicum. This similarity of chloroplast 4.5 S rRNA sequences may be used for construction of the phylogenic tree among the green plants.
Adenylate cyclase and a fatty acid spin probe detect changes in plasma membrane lipid phase separations induced by dietary manipulation of the cholesterol:phospholipid ratio
Authors: Needham Lindsey , Finnegan Irene , Houslay Miles D.
Published: July 2002

Adenylate cyclase
Cholesterol
Membrane fluidity
Glucagon
Dietary manipulation
Clofibrate
1H NMR detection of cerebral myo‐inositol
Authors: Cerdán Sebastián , Parrilla Roberto , Santoro Jorge , Rico Manuel
Published: July 2002

A previously unassigned group of prominent multiplets of the 360 MHz 1H NMR spectrum of acid stable metabolite extracts from rat brain is shown to arise from free myo‐inositol. This conclusion is derived from a systematic analysis of the high‐resolution 1H NMR spectra of brain acid extracts, in which appropriate conditions and optimal proton signals have been selected for the quantitative analysis of up to 15 metabolites. Developmental variations in the cerebral content of myo‐inositol could be readily detected using this approach, which provides a novel alternative to study myo‐inositol metabolism under physiological or pathological conditions.
Limited proteolysis of pig liver CoA synthase: evidence for subunit identity
Authors: Worrall D.Margaret , Lambert Sarah F. , Tubbs Philip K.
Published: July 2002

The bifunctional enzyme CoA synthase can be nicked by trypsin without loss of its activities. The original dimer of subunit M
r approx. 61000 yields fragments of M
r 41000 and 22000 as seen on gel electrophoresis in the presence of SDS, but the nicked enzyme retains the native M
r of 118 000. Further proteolysis occurs rapidly in the absence of protecting substrates. The N‐terminal of native CoA synthase is proline, and proteolysis exposes glycine as a second N‐terminal. This evidence strongly suggests that the subunits are identical.
A functional site of Ca2+ in the oxygen‐evolving photosystem II preparation from Synechococcus sp.
Authors: Satoh Kazuhiko , Katoh Sakae
Published: July 2002

Oxygen evolution
Electron transport
Photosystem II
Ca2+

Thermophilic cyanobacterium
Ovulation triggers oxytocin gene expression in the bovine ovary
Authors: Ivell Richard , Brackett Kevin H. , Fields Michael J. , Richter Dietmar
Published: July 2002

Oxytocin
Neurophysin
Corpus luteum
Estrous cycle
Gene expression
Identification of glycoproteins that are receptors for peanut agglutinin on immature (cortical) mouse thymocytes
Authors: De Maio Antonio , Lis Halina , Gershoni Jonathan M. , Sharon Nathan
Published: July 2002

Binding of peanut agglutinin is being widely used as a marker for immature mouse thymocytes and for the separation of these cells from the mature thymocytes. Two cell surface glycoproteins that bind peanut agglutinin were detected on unfractionated as well as immature thymocytes by lectin overlay and affinity chromatography: one of M
r between 170000 and 180000, and the other, a minor component, of M
r 110000, both of which are partially sialylated. No receptors for peanut agglutinin were detected on the mature cells, whereas desialylation experiments revealed the presence of a glycoprotein of M
r 110000. These findings were corroborated by electrophoretic analysis of cell surface glycoproteins of the isolated thymocyte subpopulations labeled in their carbohydrate moieties.
T7 and E.coli share homology for replication‐related gene products
Authors: Toh Hiroyuki
Published: July 2002

Recently, the complete nucleotide sequence of the bacteriophage T7 genome was determined and 50 genes were identified on the genome. We compared amino acid sequences of all the gene products of T7 and replication‐related gene products of E.coli. As a result, we found that T7 and E.coli share homology for each pair of exonuclease, DNA primase and helix‐destabilizing protein. For E.coli, these gene products are known to be involved in the process of discontinuous DNA replication. These observations suggest that T7 and E.coli have a common origin for a part of their replication systems.
The resolution of five linker histone subtypes from chicken erythrocytes
Authors: Harborne Nerina , Allan James
Published: July 2002

A method is described for the isolation of 4 highly purified H1 linker histone subfractions, and histone H5, from chicken erythrocytes. Fractionation is achieved under non‐denaturing conditions by elution from CMC‐25 Sephadex with an NaCl gradient. When applied to calf thymus H1, the order of subtype elution differs from that acheived on Amberlite IRC‐50 [(1966) J. Biol. Chem. 241, 5790‐5797; (1976) Biochemistry 15, 4233‐4242]. The two column types employed in series could provide a means for improving subtype purity.
Rate of exchange of Cl− between the aqueous phase and its action site in the O2 evolving reaction of photosystem II studied by rapid, ionic‐jump‐induced Cl− depletion
Authors: Itoh Shigeru , Iwaki Masaya
Published: July 2002

Rates of release and binding of Cl− from/to its action site in the O2 evolving reaction in photosystem II particles derived from spinach chloroplasts were estimated by measuring the suppression of O2 evolution by salt addition (ionic‐jump) and its recovery by the readdition of Cl−. It was estimated that depletion and rebinding of Cl− were completed within a few seconds. These results suggest that the Cl−‐action site is located in a space which is almost freely accessible to various ions in the outer medium, with no barrier to ion movements. These results can be explained by electrostatic attraction of Cl− to its action site, as was proposed in a study of anion effects on O2 evolution [(1986) Plant Cell Physiol. 27, in press].
The diurnal rhythm of liver glycogen phosphorylase: correlating changes in enzyme activity and enzymic protein
Authors: Roesler William J. , Khandelwal Ramji L.
Published: July 2002

The diurnal rhythm of phosphorylase activity in mouse liver extracts was correlated with the 24 h fluctuations in phosphorylase protein. This last measurement was made using rocket immunoelectrophoresis. The peak activity of phosphorylase appeared coincident (at 18:00 h) with the greatest amount of phosphorylase protein detected. Conversely, the lowest activity measured and lowest enzymic protein content both occurred at 02:00 h. Regression analysis revealed a significant positive correlation between enzyme activity and protein. Thus changes in the cellular concentration of this enzyme are implicated in the diurnal rhythm of liver glycogen.
Quantitative changes in the catalytic and regulatory subunits of nuclear cAMP‐dependent protein kinases type I and type II during isoproterenol‐induced growth of the rat parotid gland
Authors: Schwoch Gerhild , Freimann Astrid
Published: July 2002

To quantify the cAMP‐dependent protein kinases I and II in parotid gland nuclei independent of the enzyme activity, monospecific antisera against their subunits were applied in a sensitive enzyme immunoassay. About 3% of total catalytic subunit in the homogenate was found in the isolated nuclei. During β‐agonistinduced proliferation of the parotid gland the nuclear concentration of catalytic and regulatory subunits changed. Related to the number of nuclei, the catalytic subunit and the regulatory subunit RI increased about 3‐fold whereas the regulatory subunit RII remained unchanged.
Reappraisal of the liver benzpyrene hydroxylase synthesized de novo after treatment of rats with 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin and 3‐methylcholanthrene
Authors: Tsyrlov I.B. , Chasovnikova O.B. , Grishanova A.Yu. , Lyakhovich V.V.
Published: July 2002

The dynamics of the inductive effects of MC and TCDD upon rat liver microsomal benzpyrene hydroxylase and the main properties of the de novo synthesized hemoproteins have been compared. The inadequacy of expression of the enzyme activity per total cytochrome P‐448 content has been established. It was concluded that TCDD microsomes have a relatively low content of benzpyrene hydroxylase with a higher molecular activity than the enzyme from MC microsomes.
Interaction of actin with dansyl‐tropomyosin
Authors: Burtnick L.D. , Bhangu K.
Published: July 2002

5‐[Dimethylamino]naphthalene‐1‐sulfonyl chloride (dansyl chloride) reacts with rabbit skeletal muscle tropomyosin (TM) to yield a highly fluorescent product, DNS‐TM. The extent of modification of TM can be regulated over a wide range, 0.3–15.5 dansyl groups per TM, depending upon the temperature and duration of the reaction. However, under all conditions employed, about 15 different fluorescent tryptic peptides of TM were produced. DNS‐TM undergoes end‐to‐end polymerization at low ionic strengths, but to a somewhat lesser extent than unlabelled TM does. DNS‐TM also binds muscle F‐actin. This interaction may be followed fluorimetrically by observing a blue‐shift in emission maximum, an increase in fluorescence intensity or an increase in fluorescence polarization of the DNS‐TM complex with F‐actin.
Transbilayer reorientation of platelet‐activating factor in the erythrocyte membrane
Authors: Schneider E. , Haest C.W.M. , Deuticke B.
Published: July 2002

Platelet‐activating factor (PAF) is a phospholipid, intermediate in its structure between diacyl‐ and lysophospholipids. The reorientation of this highly bioactive compound to the inner membrane layer of human erythrocytes after its primary incorporation into the outer membrane layer has been studied. Reorientation was shown to be a slow process with an initial rate of only 0.012 h−1. It does not depend on energy supply. From the steady‐state distribution of PAF between inner and outer membrane layers, after very long incubation times (40–50 h), a preference of PAF for the outer membrane layer analogous to that of endogenous lecithin is derived. Our data indicate that the process of simple transbilayer reorientation of PAF is probably too slow to account for very fast transmembrane signal transmission or for the fast uptake and metabolism observed in certain cell types.
Oxygen dependence of vitamin K‐dependent carboxylase and vitamin K epoxidase
Authors: McTigue John J. , Suttie J.W.
Published: July 2002

A study of the oxygen requirements of the rat liver microsomal vitamin K‐dependent carboxylase and vitamin K 2,3‐epoxidase indicated that both enzymes had a K
m for O2 in the range 60–80 μM. This value was not influenced by vitamin concentration, alterations in carboxylase substrate, Mn2+, or dithiothreitol, and is consistent with the hypothesis that both activities are catalyzed by the same enzyme.
Na+‐coupled D‐glucose uptake and membrane order of enterocyte brush border membrane vesicles, under the effect of a series of N‐phenylcarbamates
Authors: Fernandez Y. , Boigegrain R.-A. , Cambon-Gros C. , Deltour P. , Mitjavila S.
Published: July 2002

The importance of the hydrophobic effect of exogenous substances and of modifications of membrane order on D‐glucose uptake are still poorly defined. Our results show that the concentrative Na+ ‐coupled D‐glucose uptake of rat enterocyte brush border membrane vesicles is inhibited by N‐phenylcarbamate derivatives. Unlike other series of lipophilic compounds inhibiting D‐glucose transport, these N‐phenylcarbamates increase the membrane order. However, since the concentrations required for membrane order increase are much greater than those active on D‐glucose uptake, the effects on lipid order cannot be resposible for the inhibition of D‐glucose uptake. Measurements of D‐glucose uptake under conditions of Na+ equilibrium show that these carbamates do not act directly on the carrier but indirectly by favouring the dissipation of the Na+ gradient.
Determination of the stoichiometry of redox‐linked proton translocation from the kinetics of pulse experiments
Authors: Krab Klaas , Wikström Mårten
Published: July 2002

Electron transport
Proton transport
Mitochondria
Effects of some substrate analogs on aerobactin synthetase from Aerobacter aerogenes 62‐1
Authors: Appanna Vasu D. , Viswanatha Thammaiah
Published: July 2002

Tricarballylic acid was the only analog of citric acid that appeared to be a substrate for aerobactin synthetase. The others, succinic acid, glutaric acid and 3‐methyl‐3‐hydroxyglutaric acid, though potent inhibitors of aerobactin synthesis, were neither activated nor utilised by the enzyme system. Aerobactin synthetase seemed to mediate the condensation of either N
6‐n‐butyryl‐N
6‐hydroxylysine, or N
6‐succinyl‐N
6‐hydroxylysine, or N
6‐acetyllysine and citric acid, in a manner analogous to that of the natural substrate, N
6‐acetyl‐N
6‐hydroxylysine.
Novel enzyme immunoassay for thyrotropin‐releasing hormone using N‐(4‐diazophenyl)maleimide as a coupling agent
Authors: Fujiwara Kunio , Saita Tetsuya
Published: July 2002

A novel enzyme immunoassay (EIA) for thyrotropin‐releasing hormone (TRH) was developed which used N‐(4‐diazophenyl)maleimide (DPM) as a new heterobifunctional agent capable of cross‐linking TRH to mercaptosuccinyl bovine serum albumin and to β‐D‐galactosidase. The resulting conjugates act as the immunogen producing anti‐TRH serum in rabbits and the enzyme marker of TRH in the EIA, respectively. This EIA with a double‐antibody technique was sensitive and reproducible in measuring TRH at concentrations as low as 50 pg per tube, and monospecific to the hormone showing no cross‐reactivity with the hormone analogue L‐pGlu‐L‐His‐L‐Pro and TRH constituents. Using this assay, the distribution of immunoreactive TRH in the brain was determined easily in rats. The use of DPM should provide a valuable new method for developing EIA hitherto possible for other peptide hormones containing neither a free carboxy nor a free amino group, using imidazole, phenolic, and indole group(s) of the amino acid as a reaction site.
Hydroperoxyfatty acids inactivate the reticulocyte lipoxygenase independently of a hydroperoxidase reaction
Authors: Rapoport S. , Härtel B. , Schewe T. , Kühn H.
Published: July 2002

From a comparison of 9Ds‐HPODE and 13Ls‐HPODE and their methyl esters as substrates and inactivating agents of reticulocyte lipoxygenase it is concluded that the compounds inactivate the enzyme independently of any hydroperoxidase reaction. The protective effect of 4‐nitrocatechol indicates the formation of Fe(III) complexes of the enzyme with the hydroperoxyfatty acid compounds prior to inactivation.
Proton‐motive force during growth of Escherichia coli in the recycling fermentor
Authors: van Verseveld Henk W. , Braster Martin , Kashket Eva R. , Stouthamer Adriaan H.
Published: July 2002

The proton‐motive force (Δp) has been determined during growth of Escherichia coli in a recycling fermentor and in a chemostat. The recycling fermentor has proven to be an easy and suitable technique for measuring Δp in growing cells, especially at low specific growth rates. Δp was determined by measuring the transmembrane gradient of protons, ΔpH, from the accumulation of benzoate anions, and the electrical gradient, ΔΨ, from the accumulation of the lipophilic cation tetraphenylphosphonium (TPP+). The accumulation of lactose was also used to calculate Δp in two lactose operon constitutive, β‐galactosidase negative relaxed mutants. In the recycling fermentor the calculated Δp values were independent of the specific growth rate and of the growth phase with both relaxed mutants. Δp values measured in the chemostat at different specific growth rates yielded the same result. Results with a wild‐type E. coli that expresses the stringent response at specific growth rates lower than 0.01 h−, corresponding to generation times greater than 70 h, showed that Δp varies inversely with specific growth rate. These results indicate that a relationship exists between Δpand the expression of the stringent response.
A 13C‐NMR study of mutant hemoglobins with altered oxygen affinity
Authors: Smith Michael L. , Norden Bo , Edlund Ulf , Romeo Paul-Henry , Rosa Jean , Paul Karl-Gustav
Published: July 2002

The 13CO‐NMR spectra of carbonylhemoglobins Saint Mandé (β 102Asn → Tyr), Malmö (β 97His → Gln), Hôtel Dieu (β 99Asp → Gly) and Ao have been determined. The positions of the 13CO resonances for hemoglobins Ao, Malmö and Hôtel Dieu were similar indicating similar ligand environments for all. The 13CO resonance for the β‐subunit of Saint Mandé was upfield‐shifted compared to the others. This is evidence that structural changes at the β 102 position directly affect iron‐ligand bonding as well as quaternary structure.
Localization of dolichols in phospholipid membranes
Authors: Lai Ching-San , Schutzbach John S.
Published: July 2002

We have used ESR methods employing spin‐labeled stearates to investigate the effects of dolichol on the motion of lipid molecules in phospholipid membranes of phosphatidylethanolamine and phosphatidylcholine. The ESR spectra show that the presence of dolichol affects the motion of the spin probes at carbon‐16, but not at carbon‐5. Similar results are obtained with phospholipid membranes comprising only phosphatidylcholine. It is suggested that dolichol molecules are present mainly in the lipid core region of phospholipid membranes.
Diacylglycerol hydrolysis in rat liver lysosomes
Authors: Kunze Hans , Hesse Bernd , Löffler Bernd-Michael
Published: July 2002

The matrix of rat liver lysosomes exhibits high hydrolytic activity towards 1,2‐diacylglycerol with an optimum at pH 4.0. The lipolytic reaction follows Michaelis‐Menten kinetics (apparent V
max 470 per mg protein; apparent K
m71 μM 1,2‐dioleoylglycerol). Formation of 1‐ and 2‐monooleoylglycerols indicates an initial attack at both the primary and secondary ester bonds. The lysosomal matrix also catalyses (re)acylation reactions, i.e. the formation of 1,2‐diacylglycerol from 2‐monoacylglycerol and free fatty acid. However, (re)acylation proceeds at a far lower rate than deacylation of diacylglycerol. Lysosomal diacylglycerol hydrolysis is sensitive towards non‐ionic detergents, cationic amphiphilic drugs and the lipase inhibitor RHC 80267.
Uncharged tRNA error damping model
Authors: Gallant Jonathan A.
Published: July 2002

Uncharged tRNA is known to bind to the ribosome in a codon‐specific fashion. In this way, cognate uncharged tRNA competes with non‐cognate aminoacyl‐tRNA. If uncharged tRNA can be aminoacylated while on the ribosome, this will damp errors due to aminoacyl‐tRNA imbalance. Kinetic analysis shows that this scheme reduces errors at ‘hungry’ codons considerably more effectively than J. Ninio's accuracy tuner model; for example, a 10‐fold decrease in cognate aminoacyl‐tRNA elicits only a 10% increase in the error frequency.
Human inhibin genes
Authors: Stewart Andrew G. , Milborrow Helen M. , Ring Jennifer M. , Crowther Carol E. , Forage Robert G.
Published: July 2002

Inhibin is a gonadal hormone involved in the non‐steroidal regulation of follicle stimulating hormone (FSH) secretion. Using the cDNAs coding for bovine inhibin A and B subunits we have identified inhibin genes within the human genome using Southern blot hybridisation techniques. The genes are likely to be present as single copies. Cloning and sequencing inhibin genes obtained from lambda libraries of human genomic DNA provide structural and sequence data on the human A and B genes. Comparison of the known inhibin gene sequences showed, in particular, that the B subunits have identical sequences in man, pigs and cattle thus demonstrating a remarkable evolutionary conservation in these genes.
Proton NMR study of the influence of heme vinyl groups on the formation of the isomeric forms of sulfmyoglobin
Authors: Chatfield Mariann J. , La Mar Gerd N. , Balch Alan.L. , Smith Kevin M. , Parish Daniel W. , LePage Teresa J.
Published: July 2002

The formation of sulfmyoglobin has been investigated for myoglobin reconstituted with hemins having vinyls replaced by hydrogens to determine the participation of the vinyl groups in the reaction processes. Green complexes are produced in all cases, proving that vinyls are not obligatory for the formation of sulfproteins. In the presence of the 4‐vinyl group, the 1H NMR spectra of the met‐cyano derivatives indicate the formation of three green species; however, the most stable of these products is not formed in the absence of this group, confirming reaction of the 4‐vinyl in this species. Two new red extractable sulfmyoglobin derivatives are formed in the absence of the 4‐vinyl group.
Ethylene glycol causes acyl chain disordering in liquid‐crystalline, unsaturated phospholipid model membranes, as measured by 2H NMR
Authors: Nicolay Klaas , Smaal Erik B. , de Kruijff Ben
Published: July 2002

2H NMR has been used to probe the effects of ethylene glycol at the level of the acyl chains in liposomes prepared from dioleoylphosphatidic acid or dioleoylphosphatidylcholine, labeled with 2H at the 11‐position of both oleic acid chains. Increasing concentrations of ethylene glycol lead to a proportional and substantial decrease in the quadrupolar splittings, measured from the 2H NMR spectra of both liposomal systems, indicative of acyl chain disordering.
Increased nuclear cyclin/PCNA antigen staining of non S‐phase transformed human amnion cells engaged in nucleotide excision DNA repair
Authors: Celis Julio E. , Madsen Peder
Published: July 2002

PCNA autoantibodies specific for cyclin/PCNA were used to determine the nuclear distribution of this protein in transformed human amnion cells (AMA) irradiated with ultraviolet light (254 nm) under conditions that induced nucleotide excision DNA repair synthesis. The results showed a striking increase in nuclear cyclin/PCNA antigen staining of non S‐phase cells that was not abolished by cycloheximide (20 μg/ml, added 2 h before irradiation), and that is most likely due to a redistribution of pre‐existing cyclin. These observations raise the possibility that cyclin/PCNA may play a role in nucleotide excision DNA repair synthesis in addition to its putative role in replicative DNA synthesis.
Absence of a unique relationship between active transport of lactose and protonmotive force in E. coli
Authors: Ghazi Alexandre , Delamourd Lourdes , Shechter Emanuel
Published: July 2002

The relationship between active transport of lactose via the lactose permease and the protonmotive force has been determined in E. coli cells using either the respiratory chain inhibitor cyanide or protonophores to decrease the protonmotive force progressively. In contradiction with the prediction of the delocalized chemiosmotic theory, two different relationships were obtained depending on the method used.
The amphiphilicity of ACP helices: A means of macromolecular interaction?
Authors: Ernst-Fonberg Mary Lou , Tucker Margie McGee , Fonberg Ignacy B.
Published: July 2002

ACP interacts with diverse proteins in an unknown way. Possibly there is a similar mode of interaction between ACP and all ACP‐binding proteins, the amphiphilic helix. The hydrophobicities of helices from 4 different ACPs were compared. Hydrophobic moment plots were prepared for ACP helices and those of many EF hand calcium‐binding proteins. Both groups of proteins occupied the same region of the plot.
The stress‐shock response of the bacterium Methylophilus methylotrophus
Authors: Watt Paul W. , North Michael J.
Published: July 2002

A sudden increase in the growth temperature of Methylophilus methylotrophus results in the synthesis of a number of unique proteins. The major heat‐shock proteins have apparent molecular masses of 83, 78, 63, 60, 16 and 14 kDa. Other stress conditions elicit a similar response, although there are significant differences in the sets of proteins produced under the various conditions. Addition of methanol induces proteins identical in size to the heat‐shock 83, 79, 63 and 14 kDa proteins and also induces unique 94, 36 and 29 kDa species. Addition of ethanol induces proteins identical in size to the 78 and 20 kDa heat‐shock proteins and the 94 and 36 kDa methanol‐induced proteins and an apparently unique 13 kDa species. Simultaneous exposure to elevated temperature and either methanol or ethanol resulted in the synthesis of all of the proteins induced by the separate treatments. The stress‐shock proteins are differentially located in cytoplasmic, periplasmic and membrane fractions.
Chemical modification of the carboxyl groups of protein substrates enhances their thrombin susceptibility
Authors: Steiner Verena , Chang Jui-Yoa
Published: July 2002

Native or denatured protein substrates which are hardly digested by thrombin can become much more efficiently cleaved by the enzyme after chemical modification of their carboxyl groups. Five antibody κ‐chains were used to demonstrate this effect. The selective cleavage sites were determined by quantitative N‐terminal analysis and N‐terminal sequencing. All five κ‐chains share the same cleavage sites at Arg‐Thr (residues 108–109), Arg‐Glu (residues 142–143, Glu side chain modified with glycine amide), Lys‐Ser (residues 207–208) and Arg‐Gly (residues 211–212). One of the major cleavage sites (Arg‐Thr) is located at the joint of the variable/constant region. The amino acids adjacent to these cleavage sites underline the proposed structural requirements for a potential thrombin substrate [(1985) Eur. J. Biochem. 151, 217–224]. This approach can facilitate the application of thrombin in generating large polypeptide fragments of proteins.
Scorpion venom inhibits carbamylcholine‐induced 86rubidium efflux from rat parotid acini
Authors: Dehaye Jean-Paul , Winand Jacques , Christophe Jean
Published: July 2002

The muscarinic agonist carbamylcholine stimulated 5‐fold 86Rb efflux from preloaded rat parotid acini. Apamin was without effect on this carbamylcholine‐induced 86Rb efflux. By contrast, the venom from Leiurus quinquestriatus (a scorpion from Israel) inhibited non‐competitively this efflux while being without effect on the carbamylcholine‐stimulated 45Ca efflux and amylase release. This heat‐resistant inhibitory effect of the venom was destroyed by boiling in the presence of dithiothreitol. These results suggest that the venom from L. quinquestriatus contains a toxin capable to block apamin‐insensitive calcium‐activated potassium channels in rat parotid acini.
Identification of different quaternary structures of beef heart cytochrome‐c oxidase by two‐dimensional polyacrylamide gel electrophoresis
Authors: Heinrichs Marc , Schönert Hansjürgen
Published: July 2002

A two‐dimensional gel electrophoresis is decribed to identify different quartemary structures of the heart cytochrome‐c oxidase. Bovine enzyme was purified and separated by discontinuous gradient polyacrylamide gel electrophoresis under nondenaturing conditions in the 1st dimension into several discrete complexes and thereupon shown to be heterodisperse in Triton X‐100 and dodecyl maltoside. A discontinuous SDS‐polyacrylamide gel electrophoresis in the 2nd dimension was used to determine the subunit composition of the isolated complexes. One of these represents the intact enzyme with 12 different polypeptides while the others have an incomplete subunit composition.
Effects of phorbol esters on steroidogenesis in small bovine luteal cells
Authors: Benhaim Annie , Herrou Michel , Mittre Herve , Leymarie Pierre
Published: July 2002

The possible influence of an activator of protein kinase C, the tumor‐promoting phorbol ester, PMA (phorbol‐12‐myristate‐13‐acetate), upon small bovine luteal cell steroidogenesis was investigated in vitro. PMA had no significant effect on basal and dibutyryl cyclic AMP (dbcAMP)‐stimulated progesterone production but markedly modulated the LH‐stimulated progesterone and cAMP productions. PMA potentiated the LH‐stimulated cAMP accumulation whatever the dose of LH used. It also potentiated the LH‐induced progesterone production in the presence of low doses of LH. Paradoxically, in the presence of maximal or submaximal effective doses of LH, PMA exerted a time‐ and dose‐dependent inhibition of progesterone synthesis. Diacylglycerol was able to mimic the effects of PMA on LH‐induced steroidogenesis. These observations suggest that the Ca2+‐ and phospholipid‐dependent protein kinase C can modulate the regulation by LH of small bovine luteal cell steroidogenesis at a step before the synthesis of cAMP. They also suggest that the interaction between LH and its receptor is able to trigger a negative regulatory signal which would be only expressed for high doses of LH and in the presence of an activator of PKC.
Maintenance of accuracy during amino acid starvation
Authors: Liljenström Hans
Published: July 2002

The kinetics of the tRNA cycle is in itself capable of keeping the translational error level almost unaffected by amino acid starvation. There is no need to assume any yet unknown mechanism or property. Kinetic analysis shows that the concentration of aminoacyl‐tRNA can stay high even for large reductions in amino‐acylation, since the pool of unchanged tRNA normally is very small. An enhanced binding of uncharged tRNA to the ribosome could increase the effect and produce an extremely efficient error damping. A similar result is obtained when EF‐Tu is partially inhibited by ppGpp.