bluuebunny/crossref_metadata_2025 huggingface dataset:
RNA structural elements for expression in Escherichia coli
Authors: Tessier Luc-Henri , Jallat Sophie , Sauvageot Martine , Crystal Ronald G. , Courtney Michael
Published: July 2002

Analysis of a series of λ cII::α1‐antitrypsin (α1AT) gene fusions of different sizes showed that increased α1AT expression correlated with the stabilisation of a particular computer‐predicted RNA secondary structure. Moreover, significant synthesis of unfused α1AT was achieved by reconstruction of this conformation to permit interaction between the upstream region of the ribosome‐binding site and the first part of the α1 AT coding sequence. This high‐level expression was dependent upon certain silent point mutations in the coding sequence, indicating that RNA primary and secondary structure determinants can operate in concert to dictate the efficiency of protein synthesis.
Modifications of 60 S ribosomal subunits induced by the ricin A chain
Authors: Paleologue Anne , Reboud Jean Paul , Reboud Anne-Marie
Published: July 2002

Incubation of 60 S ribosomal subunits with the ricin A chain reduced their stability during heat treatment. The toxin shifted the thermal denaturation curve of the subunits towards lower temperatures, in a similar way to that produced by the decrease in Mg2+ concentration. A brief heating (3 min at 57°C), which did not affect control subunit activity, enhanced protein synthesis inhibition of the toxin‐treated subunits that released more 5 S RNA, in the form of nucleoprotein complex(es) with protein L5 and phosphoproteins P1P2 (RNPH), than did heated control subunits [(1984) Eur. J. Biochem, 143, 303‐307]. No nuclease activity tested on 60 S subunits and purified 5 S and 5.8 S RNA was found associated with the toxin. The results suggest that the toxin induced a limited conformational change of the 60 S subunit, which destabilized the interaction between RNPH and the rest of the subunit.
Identification of an insulin‐like growth factor‐binding protein in human cerebrospinal fluid with a selective affinity for IGF‐II
Authors: Hossenlopp Paul , Seurin Danielle , Segovia-Quinson Berta , Binoux Michel
Published: July 2002

Human cerebrospinal fluid (CSF) has been found to contain several different molecular forms of IGF‐specific binding proteins (BPs). Qualitatively, they are similar to those present in serum, although their relative proportions are very different, as well as to those present in the culture media of brain tissue from which these BPs presumably arise. One particular form of BP is predominant in CSF. It has an M
r of 34 000, as estimated by SDS‐polyacrylamide gel electrophoresis followed by transfer onto nitrocellulose, and an isoelectric point around 5.0 based on chromatofocusing. It has a selective affinity for IGF‐II (~4 × 1010 M−1) as shown by competitive binding experiments in which biosynthetic IGF‐I was about 40‐times less potent than native IGF‐II in displacing 125I‐labelled IGF‐II. These findings are in agreement with the preponderance of IGF‐II in nervous tissue and in CSF and suggest that this BP plays an important role in the interaction of IGF‐II with its target cells.
Highly selective affinity labelling of RNA polymerase B (II) from wheat germ
Authors: Grachev M.A. , Hartmann G.R. , Maximova T.G. , Mustaev A.A. , Schäffner A.R. , Sieber H. , Zaychikov E.F.
Published: July 2002

DNA‐dependent RNA polymerase B (II) from wheat germ was modified by incubation with 4‐[N‐(β‐hydroxyethyl)‐N‐methyl]benzaldehyde esters of AMP, ADP or ATP, followed by reduction with NaBH4. Reaction of the modified enzyme with [α‐32P]UTP in the presence of various DNA templates led to a highly selective affinity labelling of the subunit with M
r 140000 by covalently linked ApU. Labelling was inhibited by 1 α‐amanitin.
On the mechanism of cytochrome oxidation in bacterial photosynthesis
Authors: Bixon Mordechai , Jortner Joshua
Published: July 2002

We propose that the unique temperature dependence of the Chance‐De Vault cytochrome oxidation reaction in Chromatium is not due to a transition from low‐temperature nuclear tunnelling to a high‐temperature activated electron transfer (ET), but rather originates from two parallel ET processes from two distinct low‐potential cytochromes to the bacteriochlorophyll dimer cation. These involve a slow activationless process, which dominates at low temperatures (T ⩽ 120 K) and an activated process, which is practically exclusive at high temperatures. This conjecture provides plausible nuclear and electronic coupling terms and structural data for the two cytochrome oxidation reactions.
Proposed alignment of helical interruptions in the two subunits of the basement membrane (type IV) collagen
Authors: Vogeli Gabriel , Horn Elizabeth , Carter Jane , Kaytes Paul S.
Published: July 2002

We have isolated a cDNA clone for part of the α2 type IV collagen (pCIV‐2‐176). Deoxynucleotide sequence analysis shows that this clone codes for 439 amino acids from the helical domain adjacent to the C‐terminal globular domain of the α2 (IV) chain. By aligning the deduced amino acid sequence of the α2 (IV) chain with the published sequence for the α1 (IV) chain, we find that all interruptions in the α1 (IV) chain coincide with an interruption in the α2 (IV) chain. Additonal interruptions in the α2 (IV) chain exist, however, three out of the four analysed only slightly disturb the collagen triple helix.
Activation of S6 kinase activity in astrocytes by insulin, somatomedin C and TPA
Authors: Pierre Michel , Toru-Delbauffe Danielle , Gavaret Jean Michel , Pomerance Martine , Jacquemin Claude
Published: July 2002

Treatment of cultured astrocytes from 2‐day‐old rat cerebral hemispheres with insulin or somatomedin C (IGF1) promoted a rapid activation of a cytosolic protein kinase which phosphorylates ribosomal protein S6. Phosphorylation of substrates currently used for protein kinase assays (histone H2B and phosvitin) was not stimulated. Neither the cyclic AMP‐dependent protein kinase activity nor that of protein kinase C was modified. Treatment of these astrocytes with TPA also promoted a rapid increase in S6 kinase activity in the cytosolic fraction. Simultaneously, protein kinase C disappeared from the cytosol. Neither cyclic AMP‐dependent protein kinase activity nor phosvitin kinase activity was modified. The effects of insulin, IGF1 and TPA were also observed in the presence of cycloheximide. Cycloheximide also potentiated their effects. These data indicate that S6 kinase activity in astrocytes is promoted from a pre‐existing molecule via the tyrosine kinase‐insulin receptor and suggest that protein kinase C is implicated in the process.
Galactosyltransferase‐dependent sialylation of complex and endo‐N‐acetylglucosaminidase H‐treated core N‐glycans in vitro
Authors: Berger Eric G. , Greber Urs F. , Mosbach Klaus
Published: July 2002

Oligomannose glycan
Ovalbumin
Endo‐β‐N‐acetylglucosaminidase H2

Invertase
(Saccharomyces cerevisiae)
Glycosylation
Characterization of protamines from four avian species
Authors: Chiva Manel , Kasinsky Harold F. , Subirana Juan A.
Published: July 2002

No data are available on the protamines of birds, with the exception of galline. We have characterized the protamines from four species of birds belonging to four different orders. All of them have very similar properties. They have been purified by carboxymethylcellulose chromatography and analyzed with respect to amino acid composition and electrophoretic behaviour. They are very arginine‐rich proteins (63.4–67.3%) but do not contain lysine. Serine (12.0–18.2%), tyrosine (5.8–9.0%) and glycine (4.5–7.1%), along with arginine, make up the bulk of the amino acid residues in these molecules. The electrophoretic mobility of bird protamines in acetic acid‐urea‐polyacrylamide gels is intermediate between that of somatic histones and salmine. The molecular size, estimated from amino acid analysis and electrophoretic migration, is 65 ± 5 amino acid residues.
Activation of F1 ‐ATPase isolated from potato tuber mitochondria
Authors: Glaser E. , Hamasur B. , Norling B. , Andersson B.
Published: July 2002

The ATP‐hydrolyzing activity of F1‐ATPase purified from potato tubers mitochondria was stimulated 2‐ and 3.5‐fold by anions, chloride and bicarbonate, respectively, and 5.5‐ and 6.5‐fold by detergents, octyl glucoside and lauryl dimethylamine oxide (LDAO), respectively. The maximal specific activity of the activated F1, 129 μmol/min per mg protein is the highest activity of plant mitochondrial F1 hitherto reported and exceeds several‐fold values reported earlier. In the absence of activators F1‐catalyzed ATP hydrolysis exhibits non‐linear double‐reciprocal plots of [ATP]−1 vs v
−1 indicative of negative cooperativity, while in the presence of activators, linear plots are observed. It is suggested that the activators reduce the cooperativity originating from the interaction between different subunits of the enzyme.
Thyroid hormone uptake into the cell and its subsequent localisation to the mitochondria
Authors: Hafner Roderick P.
Published: July 2002

The nature of thyroid hormone uptake into the cell and the possible involvement of the serum carrier proteins and receptor‐mediated endocytosis in this process are reviewed. The evidence that there is a specific thyroid hormone‐binding receptor in the inner mitochondrial membrane and the relation of this to the adenine nucleotide translocator is discussed. Direct effects of thyroid hormone on mitochondrial function that might be mediated by such a receptor are also considered.
Identification of two forms of 6‐phosphofructo‐2‐kinase in yeast
Authors: Aragón Juan J. , Gómez María-Esther , Gancedo Carlos
Published: July 2002

Two forms of 6‐phosphofructo‐2‐kinase have been identified in Saccharomyces cerevisiae by their different chromatographic behaviour on CM‐Sephadex C‐50. One of them was not adsorbed and represented ∼ 30% of the eluted activity. The other one emerged at about 120 mM KCl. A molecular mass of 120 kDa was found for both of them. No differences in kinetic behaviour in susceptibility to activation by cAMP‐dependent protein kinase were found between the two forms.
Conformation of colicin A: Apparent difference between cytoplasmic and extracellular polypeptide chain
Authors: Knibiehler Martine , Lazdunski Claude
Published: July 2002

Cytoplasmic colicin A has the ability to bind to membranes and to form stable dimers. This form remains stable even in the presence of 1% SDS at 25°C. Both of these properties were not observed for extracellular colicin A suggesting a possible difference in the conformation between cytoplasmic and extracellular colicin A.
Immunological identification of the polypeptide bands in the SDS‐polyacrylamide gel electrophoresis of photosystem II preparations
Authors: Satoh Kimiyuki , Fujii Yoko , Aoshima Tatsuo , Tado Tohru
Published: July 2002

Antibodies raised against each of the constituent proteins of the photosystem II core complex, i.e. against the 47 kDa protein (psbB product), the 43 kDa protein (psbC product), cytochrome b‐559 (psbE and psbF products), the psbA product expressed in E. coli or against a synthetic oligopeptide corresponding to a part of the sequence of psbD gene, were utilized to determine the origin of higher molecular mass bands exhibited by SDS‐polyacrylamide gel electrophoresis of photosystem II preparations, and to identify the two medium‐size polypeptides in the 30 kDa region of the recently isolated photosystem II reaction center [(1987) Proc. Natl. Acad. Sci. USA 84, 109–112]. The result of analysis clearly indicated that the photosystem II reaction center consists entirely of D‐1 (psbA product), D‐2 (psbD product) and cytochrome b‐559.
The prephenate dehydrogenase component of the bifunctional T‐protein in enteric bacteria can utilize L‐arogenate
Authors: Ahmad Suhail , Jensen Roy A.
Published: July 2002

The prephenate dehydrogenase component of the bifunctional T‐protein (chorismate mutase:prephenate dehydrogenase) has been shown to utilize L‐arogenate, a common precursor of phenylalanine and tyrosine in nature, as a substrate. Partially purified T‐protein from Klebsiella pneumoniae and from Escherichia coli strains K12, B, C and W was used to demonstrate the utilization of L‐arogenate as an alternative substrate for prephenate in the presence of nicotinamide adenine dinucleotide as cofactor. The formation of L‐tyrosine from L‐arogenate by the T‐protein dehydrogenase was confirmed by high‐performance liquid chromatography. As expected of a common catalytic site, dehydrogenase activity with either prephenate or L‐arogenate was highly sensitive to inhibition by L‐tyrosine.
Isolation and identification of a fourth subunit in the membrane part of the chloroplast ATP‐synthase
Authors: Fromme Petra , Gräber Peter , Salnikow Johann
Published: July 2002

The subunit composition of highly active purified ATP‐synthase from chloroplasts, CF0F1, was investigated by SDS gel electrophoresis. An additional subunit of CF0, was detected with an apparent molecular mass of 20 kDa. It is stained weakly with Coomassie blue but very strongly with silver. This subunit was isolated on a preparative SDS gel and the N‐terminal amino acid sequence analyzed. It shows that the 20 kDa protein is identical with the protein encoded by the spinach chloroplast gene atpI, called subunit IV [(1986) Mol. Genet. 203, 117–128]. However, in comparison to the gene‐derived sequence, the first 18 amino acids are missing, indicating N‐terminal processing.
Acetylcholinesterase as polyelectrolyte in reaction with cationic substrates
Authors: Tóugu V. , Pedak A. , Kesvatera T. , Aaviksaar A.
Published: July 2002

It is shown that the salt effect in acetylcholinesterase‐catalyzed hydrolysis of 2‐(N‐methylmorpholinium) ‐ethylacetate can be quantitatively described by the equation log(k
2/K
S) = log(k
2/K
S)° — ψlog[M+Z] following from Manning's polyelectrolyte theory; the ψ values for salts with univalent and bivalent cations at different pH values of the reaction medium were in accordance with the conclusions of the theory. Manning's polyelectrolyte theory seems to be a useful framework for studying salt effects in the reactions of charged substrates with enzymes as globular polyions.
Characterization of the nucleotide tight‐binding sites of the isolated mitochondrial F1‐ATPase
Authors: Milgrom Ya.M. , Murataliev M.B.
Published: July 2002

The properties of the nucleotides tightly bound with mitochondrial F1‐ATPase were examined. One of three bound nucleotide molecules is localized at the site with K
dR̃10−7 M and released with k
off∼0.1 s−1. The second nucleotide molecule is bound with the enzyme with K
d ∼10−8 M and k
off for its dissociation is 3 × 10−4 s−1. The third is never released even in the presence of 1 mM ATP or ADP. The last two nucleotides are believed to be bound at the noncatalytic sites of F1‐ATPase. Pyrophosphate promotes liberation of two releasable nucleotide molecules, decreasing the affinity of the enzyme to AD(T)P. From the results obtained it follows that the only suitable criterion for localization of the nucleotide at the F1‐ATPase catalytic site is the high rate (k
off ≧ 0.1 s−1) of its spontaneous release.
Voltage gating in porin channels
Authors: Lakey Jeremy H.
Published: July 2002

Data from experiments in which porin channels are reconstituted into planar bilayer membranes are reviewed for their relevance to porin channel gating in vivo. Contradictory evidence concerning voltage gating indicates that the different results may stem from the variety of purification techniques employed. The likelihood of voltage gating as a property of E. coli porins in vivo is discussed in relation to the possible magnitude of the membrane potential across tho outer membrane.
Binding of phosphorylated and dephosphorylated heavy meromyosin to F‐actin
Authors: Szczçsna Danuta , Sobieszek Apolinary , Ka̧kol Irena
Published: July 2002

The effect of myosin light chain phosphorylation in skeletal muscle was investigated with respect to the binding affinity of phosphorylated and dephosphorylated heavy meromyosin (HMM) for F‐actin in the absence of ATP. For phosphorylated HMM the affinity was 2.5‐times weaker in the presence of Ca2+ as in its absence (HMM divalent binding sites saturated only with Mg). For dephosphorylated HMM the reverse was true, the binding being 2.4‐times higher in the presence of Ca2+.
Probing DNA polymerase α with monoclonal antibodies
Authors: Zahradka Peter
Published: July 2002

DNA polymerase α was purified from human KB cells by immunoaffinity chromatography. Enzyme activity was inhibited by three different monoclonal antibodies (SJK‐132, SJK‐211, SJK‐287). Kinetic analysis showed that each antibody neutralized polymerase activity by a different mechanism. SJK‐132 was competitive with DNA indicating it interacts with the DNA binding domain of the polymerase. SJK‐287 showed a biphasic response to dCTP suggesting two dCTP binding sites exist on polymerase α. SJK‐211 was noncompetitive with DNA, dCTP and dATP.
Bioenergetics of dihydrostreptomycin transport by Escherichia coli
Authors: Goss Stephen R. , Spicer Alan B. , Nichols Wright W.
Published: July 2002

Previous demonstrations of the irreversibility of dihydrostreptomycin transport across the cytoplasmic membrane of Escherichia coli were not due to decreases in the magnitude of the cytoplasmic membrane potential (Δψ). Irreversibility was probably not due to ATP hydrolysis being coupled to transport, because the rate of energy‐dependent dihydrostreptomycin uptake was unaffected by 10‐fold reduction in the cellular ATP level.
Structural differences between oxidized and reduced thioredoxin monitored by two‐dimensional 1H NMR spectroscopy
Authors: Dyson H.Jane , Holmgren Arne , Wright Peter E.
Published: July 2002

Two‐dimensional high resolution NMR techniques have been applied to study the structural differences between the oxidized and reduced forms of Escherichia coli thioredoxin in solution. Sequential proton resonance assignments indicate only limited conformational changes; major chemical shift differences are found for a few residues in a β‐strand immediately preceding the active site S◀S bridge and the active site itself. Additional resonance shifts are observed for several residues distant in the primary sequence. The X‐ray structure of oxidized thioredoxin shows that these residues form a flat hydrophobic surface, close to the active site S◀S bridge, which is probably involved in interactions with other protein molecules.
The muscarinic receptor subtype in mouse pancreatic B‐cells
Authors: Henquin J.C. , Nenquin M.
Published: July 2002

Isolated mouse islets were used to identify the muscarinic receptor subtype present in pancreatic B‐cells. We thus compared the inhibitory potencies of atropine (non‐specific), of pirenzepine (specific for M1 receptors) and of compound AF‐DX 116 (specific for cardiac M2 receptors) on acetylcholine‐induced insulin release, 86Rb+ efflux and 45Ca2+ efflux. The three antagonists inhibited all effects of acetylcholine, but EC50 values were markedly different: atropine = 1.5–5 nM, pirenzepine = 0.6–1.7 μM and AF‐DX 116 = 1.7–11 μM. The results did not suggest that the various effects of ACh could result from the activation of different subtypes of receptors. It is concluded that muscarinic receptors of pancreatic B‐cells belong to an M2 subtype distinct from the cardiac M2 receptors.
rRNA‐protein neighbourhood in Escherichia coli 70 S ribosomes and 70 S initiation complex Probing by bifunctional Pt(II)‐containing reagent
Authors: Chistyakov P.G. , Abdukayumov M.N. , Veniaminova A.G. , Vladimirov S.N. , Graifer D.M. , Kazakov S.A. , Karpova G.G.
Published: July 2002

The cleavable homobifunctional reagent dichloro[N,N,N′,N′‐tetrakis(2‐aminoethyl)‐1,6‐hexamethylenediamminediplatinum(II)] dichloride was used for studying rRNA‐protein cross‐links in free 35S‐labelled 70 S ribosomes and within initiation complex ribosome · AUGU6 · fMet‐tRNAMet
f. It was shown that the sets of proteins cross‐linked to 16 S and 23 S rRNA in free 70 S ribosomes and in 70 S initiation complex do not differ significantly. The authors are the first to demonstrate most of the 23 S rRNA‐protein cross‐links and some 16 S rRNA‐protein cross‐links, in particular those with L7/L12 protein.
Intramitochondrial factors controlling hepatic fatty acid oxidation at weaning in the rat
Authors: Decaux Jean-François , Robin Danielle , Robin Pierre , Ferré Pascal , Girard Jean
Published: July 2002

Fatty acid oxidation was studied in isolated liver mitochondria of rats during the suckling‐weaning transition. The oxidation rate of oleyl‐CoA and palmitoylcarnitine was reduced 2.5‐fold in rats weaned on a high‐carbohydrate diet compared to suckling rats, when acetyl‐CoA produced by β‐oxidation was directed towards ketone‐body synthesis. Weaning on a high‐fat diet minimized this change. Channeling of acetyl‐CoA towards citrate synthesis doubled the oxidation rate of both substrates in HC‐weaned rats. Thus, in addition to changes in carnitine palmitoyltransferase I activity, the β‐hydroxymethylglutaryl‐CoA synthase pathway is also involved in the decreased fatty acid oxidation at weaning. This was confirmed by measurement of β‐hydroxymethylglutaryl‐CoA synthase pathway activity.
Pathways of calcium release from heavy sarcoplasmic reticulum vesicles isolated from rabbit skeletal muscle
Authors: Rubtsov Alexander M. , Quinn Peter J. , Boldyrev Alexander A.
Published: July 2002

The active uptake and efflux of Ca2+ from suspensions of vesicles from heavy rabbit muscle sarcoplasmic reticulum have been examined using the antipyrylazo III dye method in the presence of various nueleotide triphosphate substrates to support active Ca2+ accumulation. On addition of ATP, Ca2+ is rapidly accumulated and maintained at high internal concentrations until the substrate for pump protein is exhausted. Ca2+ ‐induced Ca2+ release which is inhibited by ruthenium red can be demonstrated. The kinetics of Ca2+ release via these channels is different from the Ca2+ efflux observed after substrate exhaustion. This rate was found to be dependent on the type of nucleotide triphosphate, decreasing in the order ATP > GTP > CTP > ITP UTP. It is suggested that different conformations of the Ca2+ pump protein induced by the different substrates may result in the creation of pathways for the facilitated diffusion of Ca2+.
The BChlc/e‐binding polypeptides from chlorosomes of green photosynthetic bacteria
Authors: Wagner-Huber Regula , Brunisholz René , Frank Gerhard , Zuber Herbert
Published: July 2002

A 6.3 kDa polypeptide has been isolated from chlorosomes of the green photosynthetic bacterium Pelodictyon luteolum, and its complete amino acid sequence has been determined. It exhibits an overall homology of 30% to the Bchlc‐binding protein of Chloroflexus aurantiacus. Preliminary results from the N‐terminal sequence analyses of the analogous polypeptides isolated from Chlorobium limicola, Prosthecochloris aestuarii and chlorobium phaeovibrioides revealed a highly conserved sequence. This protein is suggested to be the Bchlc/e‐binding polypeptide in the family of the Chlorobiaceae.
Primary structure of rabbit sperm protamine, the first protamine of its type with an aberrant N‐terminal
Authors: Ammer H. , Henschen A.
Published: July 2002

Rabbit protamine was extracted from S‐(pyridylethylated) sperm cell nuclei with hydrochloric acid and then isolated by reversed‐phase HPLC. The primary structure was determined by amino acid sequence analysis of the total protein and of fragments obtained by digestion with endoproteinase Lys‐C and thermolysin. The protamine contains 49 amino acid residues and is clearly homologous with mammalian type 1 protamines, 47% of the positions being invariant. Surprisingly, rabbit protamine possesses an N‐terminal valine residue, whereas all mammalian and several non‐mammalian protamine sequences of this type start with alanine, the N‐terminal region being remarkably conserved during evolution.
Type I protein is a slow isoform of troponin T
Authors: Schmitt T. , Pette D.
Published: July 2002

Type I protein, a myofibrillar protein thought to be specific to slow‐twitch skeletal muscle fibers, was purified. Two‐dimensional electrophoresis indicated its identity with the purified slow troponin‐T1s isoform. Immunochemical analyses using antibodies raised against type I protein and slow Tn‐T1s, further substantiated the identity of the two proteins.
Antibodies against basic fibroblast growth factor inhibit the autocrine growth of pulmonary artery endothelial cells
Authors: Sakaguchi Masao , Kajio Tomoko , Kawahara Kenji , Kato Koichi
Published: July 2002

Anti‐recombinant human basic fibroblast growth factor (rbFGF) antibodies efficiently inhibited the basal proliferation of bovine pulmonary artery endothelial (BAE) cells. The cell‐free extract of BAE cells stimulated the proliferation of bovine capillary endothelial cells and this activity was completely abolished by the antibodies. Furthermore, on heparin HPLC the activity was eluted at exactly the same retention time as that for authentic pituitary bFGF. These observations directly indicate that the BAE cells produce bFGF that stimulates their own basal growth by binding to specific receptors expressed on the cell surface.
cDNA clones completing the nucleotide and derived amino acid sequence of the alpha 1 chain of basement membrane (type IV) collagen from mouse
Authors: Wood Linda , Theriault Nicole , Vogeli Gabriel
Published: July 2002

Six cDNA clones add 3549 nucleotides to the DNA sequence of the alpha 1 chain of basement membrane (type IV) collagen. Thus the complete nucleotide and derived amino acid sequence of the alpha 1 type IV collagen with 5007 nucleotides coding for 1669 amino acids with a calculated M
r of 160 827 is known. The six cDNA clones cover the putative N‐terminal signal peptide, the 7 S region and two thirds of the helical region extending into the previously published murine nucleotide sequence [(1986) Gene 43, 301]. The protein sequence for 289 amino acids of the helical region adjacent to the 7 S region has not previously been published for any species.
How relevant is the reoxidation of ferrocytochrome c by hydrogen peroxide when determining superoxide anion production?
Authors: Turrens Julio F. , McCord Joe M.
Published: July 2002

In a recent publication [(1987) FEBS Lett. 210, 195–198] the authors claim the use of cytochrome c to detect superoxide anion underestimates the real rate of superoxide anion formation on the basis that: (i) the rate of uric acid formation by xanthine oxidase is about 4‐fold faster than the rate of cytochrome c reduction and (ii) hydrogen peroxide formed upon dismutation of the superoxide anion generated by xanthine oxidase is capable of reoxidizing ferrocytochrome c. That paper may have been misleading for readers not very familiar with the field of oxygen radicals, since both assumptions are, in fact, incorrect. In this report we demonstrate that the build up in concentration of H2O2 during most reactions in which superoxide anion is being produced is not enough to affect the rate of cytochrome c reduction. Our results suggest that the authors may have been misled by an artifact due to exposure of the samples containing H2O2 to UV light, which generates hydroxyl radicals by photolysis.
Chlorophyll dichroism of three‐dimensional crystals of the light‐harvesting chlorophyll a/b‐protein complex
Authors: Kühlbrandt W. , Becker A. , Mäntele W.
Published: July 2002

Thin three‐dimensional crystals of the light‐harvesting chlorophyll a/b‐protein complex from pea chloroplast membranes were investigated by microspectrophotometry. Measurements of tilted crystals revealed pronounced linear dichroism in a direction perpendicular to the crystal plane but no observable dichroism in the crystal plane. Qy transition moments of chlorophylls were rotationally isotropic with respect to the crystal plane and partially aligned in this plane. Qx transition moments showed no preferential orientation and appeared to be wholly isotropic. The orientation of transition moments in the crystal was consistent with three‐fold symmetry of the light‐harvesting complex indicated by the crystal structure. The linear dichroism of the crystals reflected the optical properties of the complex in the photosynthetic membrane, indicating a highly symmetrical arrangement of antenna chlorophylls.
myo‐Inositol 1,4,5‐trisphosphorothioate is a potent competitive inhibitor of human erythrocyte 5‐phosphatase
Authors: Cooke Allan M. , Nahorski Stefan R. , Potter Barry V.L.
Published: July 2002

The effect of the myo‐inositol 1,4,5‐trisphosphate (IP3) analogue, myo‐inositol 1,4,5‐trisphosphorothioate (IPS3) on the dephosphorylation of D‐5‐[32P]IP3 by the 5‐phosphatase from human erythrocyte membranes has been investigated. DL‐IPS3 was found to act as a competitive inhibitor with a K
i of 6 μM, making it the most potent inhibitor currently available for this enzyme. L‐IP3 inhibited the enzyme with a K
i of 124 μM and was more potent than D‐2,3‐diphosphoglycerate (K
i 978 μM).
Chlorophyll and cytochrome b‐559 content of the photochemical reaction center of photosystem II
Authors: Dekker Jan P. , Bowlby Neil R. , Yocum Charles F.
Published: July 2002

Photosystem II reaction centers comprised of the D1, D2 and cytochrome b‐559 polypeptides were isolated from well‐defined oxygen‐evolving reaction center preparations using either a combination of LiClO4 and dodecylmaltoside, or Triton X‐100 alone. Yields of chlorophyll and cytochrome b‐559 for both preparative methods were compared, and pigment contents were compared based on 2.0 b‐559 per reaction center, a standard derived from photosystem II components found in the starting material. Results obtained with dodecylmaltoside suggest that the reaction center of photosystem II binds 10–12 Chl a along with 2 Cyt b‐559 molecules. Reaction centers prepared with Triton X‐100 bind about 8 Chl a per 2 Cyt b‐559 molecules, a finding which indicates that Triton X‐100 extracts pigments from the reaction center polypeptides. Our results contradict the widely held notion that the pigment binding properties of the photosystem II reaction center are similar to those of the bacterial reaction center.
Energy transduction at the catalytic site of enzymes: Hydrolysis of phosphoester bonds and synthesis of pyrophosphate by alkaline phosphatase
Authors: Nayudu Ramachandra V. , de Meis Leopoldo
Published: July 2002

Alkaline phosphatase from mouse intestinal epithelial cells catalyzes the synthesis of pyrophosphate from Pi during hydrolysis of either glucose 6‐phosphate, ATP, ADP, inorganic pyrophosphate or p‐nitrophenylphosphate. The rate of pyrophosphate synthesis is increased by MgCl2 and by decreasing the pH of the medium from 8.5 to 6.0. The data presented indicate that at the catalytic site of alkaline phosphatase the energies of hydrolysis of the phosphoserine residue and of pyrophosphate are different from those measured in aqueous solutions.
Leucine transport in plasma membrane vesicles of Saccharomyces cerevisiae
Authors: Calahorra M. , Opekarová M. , Ramirez J. , Peña A.
Published: July 2002

Yeast plasma membrane vesicles were obtained by the fusion of liposomes with purified yeast membranes by means of the freeze thaw‐sonication technique. Beef heart mitochondria cytochrome‐c oxidase was incorporated into the vesicles. Addition of substrate (ascorbate/TMPD/cytochrome c) generated a membrane potential negative inside, and an alkaline pH gradient inside the vesicle, that served as the driving force for leucine transport. Both ΔpH and ΔΨ could drive leucine transport. When ΔpH was increased in the presence of valinomycin and potassium, at the expense of ΔΨ, leucine uptake increased by 10%.
A theoretical study of the acidification of the rhinovirus capsid
Authors: Warwicker J.
Published: July 2002

Electrostatic calculations for human rhinovirus 14 indicate that histidine‐base residue pairs in the region of a β‐strand interaction between pentamers may be involved in a pH‐induced process that leads to the release of viral RNA. Other picornavirus sequences are examined for these residue pairs, a subset of which is present in enteroviruses. Foot and mouth disease virus possesses one of the residue pairs, and cardioviruses, which undergo a separate pH and halide ion‐induced capsid dissociation, possess none.
Solution conformation of endothelin determined by nuclear magnetic resonance and distance geometry
Authors: Endo Satoshi , Inooka Hiroshi , Ishibashi Yoshihiro , Kitada Chieko , Mizuta Eiji , Fujino Masahiko
Published: July 2002

Endothelin; Vasoconstrictor peptide; Three‐dimensional structure; NMR, 1H; Distance geometry
Bacterial ‘histone‐like protein I’ (HLP‐I) is an outer membrane constituent?
Authors: Hirvas Laura , Coleman Jack , Koski Pertti , Vaara Martti
Published: July 2002

The nucleoid‐associated ‘histone‐like protein I’ (HLP‐I) protein of E. coli was found to be homologous with the cationic 16‐kDa outer membrane protein OmpH of Salmonella typhimurium. Deduced from the nucleotide sequence, the HLP‐I protein has 91% identical residues with the OmpH protein. Both proteins have very similar cleavable signal sequences. The nucleotide sequence similarity between the corresponding genes hlpA and ompH is 87%. The ompH gene is located in a gene cluster resembling the hlpA‐ORF17 region of E. coli which is close to the Ipx genes involved in the biosynthesis of lipopolysaccharides. The localization of the OmpH/HLP‐I protein in the cell is discussed.
Solubilization of soybean membrane binding sites for fungal β‐glucans that elicit phytoalexin accumulation
Authors: Cosio Eric G. , Frey Thomas , Ebel Jürgen
Published: July 2002

Soybean membranes contain high‐affinity binding sites for fungal β‐glucans. These sites may play a role in the recognition by soybean tissues of fungal phytoalexin elicitors. We have solubilized β‐glucan‐binding activity from microsomal membranes using two C12,‐alkyl zwitterionic detergents, Zwittergent 3‐12 (ZW 3‐12) and the lysolecithin analog l‐dodecyl‐2‐deoxy‐phosphorylcholine (ES12H). The solubilized binding sites displayed identical affinity for β‐glucans as that found in membranes (K
d= 11‐34 nM). Detergent‐protein micelles with glucan binding activity eluted with approximate M
r values of 300000 in ZW 3‐12 and 380000 in ES12H in gel permeation chromatography. Maximal binding activity eluted from a chromatofocusing column in the pH range between 6.2 and 6.6 with both ES12H and ZW 3‐12, suggesting an apparent pIclose to neutral.
Effect of ATP on the activity of bovine heart mitochondrial b‐c1 complex
Authors: Lorusso Michele , Cocco Tiziana , Minuto Michele , Papa Sergio
Published: July 2002

The effect of ATP on the reductase activity of purified bovine heart b‐c
1 complex was studied. ATP stimulates the steady‐state activity and the antimycin‐insensitive pre‐steady‐state reduction of b and c
1 cytochromes, also causing changes of kinetic properties of the enzyme. There is no absolute specificity for ATP since other polyvalent anions such as EDTA and EGTA produce similar effects in the micromolar range. It is proposed that ATP stimulates the activity of the b‐c
1 complex, chelating inhibitory cation(s), exerting a modulatory action on the enzyme.
Novel putative protein tyrosine phosphatases identified by the polymerase chain reaction
Authors: Nishi Masahiro , Ohagi Shinya , Steiner Donald F.
Published: July 2002

Protein tyrosine phosphatases (PTPases) are a family of enzymes that specifically dephosphorylate phosphotyrosyl residues in selected protein substrates. To more fully understand the regulatory role of protein tyrosine phosphorylation and dephosphorylation in cellular signal transduction, characterization of PTPases is essential. Using the polymerase chain reaction and degenerate oligonucleotide primers corresponding to conserved amino acid sequences within the catalytic domain of PTPases, we have identified 11 PTPase‐related human liver cDNA sequences. Five of these have not been described previously. These results indicate that, like protein tyrosine kinases. PTPases may also comprise a gene family with a large number of members.
Are there isoenzymes of cytochrome c oxidase in Paracoccus denitrificans?
Authors: Raitio Mirja , Pispa Johanna M. , Metso Tuula , Saraste Matti
Published: July 2002

We have used a gene replacement strategy to delete the previously isolated gene [(1987) EMBO J. 6, 2825‐2833] for the cytochrome c oxidase subunit I from Paracoccus denitrificans. The resulting mutant was still able to synthesize active cytochrome c oxidase. This led us to look for another locus which could completely suppress the mutation. In this study we report the isolation of a second gene encoding subunit I. An open reading frame coding for cytochrome c 550 was found upstream from this gene. We suggest that there are isoenzymes of cytochrome c oxidase (cytochrome aa
3) in this bacterium.
Substrate‐dependent inhibition of protein kinase C by specific inhibitors
Authors: Junco María , Díaz-Guerrá María José M. , Bosca Lisardo
Published: July 2002

Protein kinase C (PKC) and its proteolysis‐derived protein kinase independent of Ca2+ and phospholipids (PKM), were purified from rat brain. By using histone HI and protamine as substrates, we assayed the effect of several inhibitors of PKC and PKM. The inhibition turned out to be dependent on both the nature of the kinase and the type of substrate assayed. These results may help to interpret the different responses elicited by PKC inhibitors in vivo.
Amino‐terminal amino acid sequence of beef heart mitochondrial coupling factor B
Authors: Kantham Lakshmi , Raychowdhury Raktima , Ogata Kathleen K. , Javed Ali , Rice John , Rao Sanadi D.
Published: July 2002

Bovine heart mitochondrial coupling factor B was isolated and purified to homogeneity in its active form. The amino‐terminal amino acid sequence of the alkylated protein was determined. Two chains with exactly the same sequence except for the presence of an additional Phe at the aminoterminus on one of them were obtained. The 55 amino acid sequence appears to be largely hydrophilic with several charged amino acid residues. This sequence showed no homology with the E. coli unc operon, oligomycin sensitivity conferring protein, or coupling factor 6 or any protein in the data base.
SecE‐dependent overproduction of SecY in Escherichia coli
Authors: Matsuyama Shin-ichi , Akimaru Jiro , Mizushima Shoji
Published: July 2002

The secY and secE genes were individually cloned and placed under the control of the tac promoter on plasmids. Induction with isopropyl‐β‐D‐thiogalactopyranoside resulted in the overproduction of SecE, but not that of SecY. The simultaneous induced expression of both genes in the same cells resulted in the overproduction of SecY together with that of SecE. SecY and SecE thus overproduced were localized in the cytoplasmic membrane as those expressed at the normal levels were. It is suggested that SecY and SecE interact with each other in the cytoplasmic membrane. The numbers of the SecY and SecE molecules per cell were estimated.
Demonstration of two isoforms of subunit VIIa of cytochrome c oxidase from human skeletal muscle
Authors: Van Beeumen Jozef J. , Van Kuilenburg André B.P. , Van Bun Stefaan , Van den Bogert Coby , Tager Joseph M. , Muijsers Anton O.
Published: July 2002

Two different isoforms of subunit VIIa have been found in cytochrome c oxidase isolated from human skeletal muscle. The first 22 residues of the N‐terminal amino acid sequences showed 5 differences. Our results provide the first conclusive evidence for the existence of cytochrome c oxida isoenzymes in man. Since the two cytochrome c oxidase isoforms were both present in skeletal muscle tissue, though not necessarily in the same cell type, this suggests that human cytochrome c oxidase isoforms are not strictly tissue‐specific. These findings may have important implications for the elucidation of genetic diseases in man in which a deficiency of cytochrome c oxidase is restricted to certain tissues.
Polypeptide composition of higher plant photosystem I complex
Authors: Ikeuchi Masahiko , Hirano Atsushi , Hiyama Tetsuo , Inoue Yorinao
Published: July 2002

High resolution gel electrophoresis of the native photosystem I complex retaining light‐harvesting chlorophyll complex revealed the presence of three low‐molecular‐mass proteins of 7, 4.1 and 3.9 kDa in spinach, and 6.8, 4.4 and 4.1 kDa in pea, in addition to the other well‐characterized higher‐molecular‐mass components. Upon further detergent treatment to deplete light‐harvesting chlorophyll complex, the 7 kDa and 4.1 kDa proteins were removed from the photosystem I core complex of spinach, while the 3.9 kDa protein was retained. N‐terminal sequencing demonstrated that the 4.1 kDa proteins from both spinach and pea correspond to the gene product of ORF42/44 in chloroplast genome of liverwort and higher plants, which was previously hypothesized as a photosystem I gene (psaJ) based on sequence homology with the cyanobacterial photosystem I component of 4.1 kDa [(1989) FEBS Lett. 253, 257‐263]. N‐terminal sequence of the spinach 3.9 kDa and pea 4.4 kDa proteins fitted with chloroplast ORF36/40 (psaI) although no homologue has been found in cyanobacteria. The spinach 7 kDa and pea 6.8 kDa proteins correspond to the nuclear‐encoded psaK product and significantly matched with the N‐terminal sequence of the cyanobacterial 6.5 kDa subunit. The evolutional conservation of the psaJ and psaK seems to suggest their intrinsic role(s) in photosystem I.
Inhibition of aspartic proteinases by propart peptides of human procathepsin D and chicken pepsinogen
Authors: Fusek M. , Mareš M. , Vágner J. , Voburka Z. , Baudyš M.
Published: July 2002

Two propart peptides of aspartic proteinases. the propart peptide of chicken pepsin and human cathepsin D, respectively, were investigated from the point of view of their inhibitory activity for a set of aspartic proteinases. These peptides display a very broad inhibitory spectrum. The strongest inhibition was observed for pepsin A‐like proteinases where propart peptides can be used as titrants of active enzymes.
Molecular cloning and expresion of a protein‐tyrosine phosphatase showing homology with transcription factors Fos and Jun
Authors: Swarup G. , Kamatkur S. , Radha V. , Rema V.
Published: July 2002

A cDNA clone coding for a protein‐tyrosine phosphatase (PTPase) was isolated from a rat spleen cDNA library. Nucleotide sequence of the clone showed an open reading frame coding for a polypeptide of 363 amino acids. Expression of this clone in E. coli in an expression vector showed PTPase activity. The non‐catalytic region of this PTPase located at the carboxy terminus shows homology with the basic domains of transcription factors Fos and Jun. Northern blot analysis showed that a 1.7 kb transcript was present in many tissues and cells, the highest level being in macrophages. This PTPase is a rat homolog of human T‐cell PTPase although it shows 3 large deletions in the carboxy terminal non‐catalytic region.
Structural features of stomach aldehyde dehydrogenase distinguish dimeric aldehyde dehydrogenase as a ‘variable’ enzyme ‘Variable’ and ‘constant’ enzymes within the alcohol and aldehyde dehydrogenase families
Authors: Yin Shih-Jiun , Vagelopoulos Nikolaos , Wang Sung-Ling , Jörnvall Hans
Published: July 2002

Stomach aldehyde dehydrogenase was structurally evaluated by analysis of peptide fragments of the human enzyme and comparisons with corresponding parts from other characterized aldehyde dehydrogenases. The results establish a large part of the structure, confirming that the stomach enzyme is identical to the inducible or tumor‐derived dimeric aldehyde dehydrogenase. In addition, species variations between identical sets of different aldehyde and alcohol dehydrogenases reveal that stomach aldehyde dehydrogenase exhibits a fairly rapid rate of evolutionary changes, similar to that for the likewise ‘variable’ classical alcohol dehydrogenase, sorbitol dehydrogenase, and cytosolic aldehyde dehydrogenase but in contrast to the ‘constant’ class III alcohol dehydrogenase and mitochondrial aldehyde dehydrogenase. This establishes that rates of divergence in the aldehyde and alcohol dehydrogenases are unrelated to subunit size or quaternary structure, highlights the unique nature of class III alcohol dehydrogenase, and positions the stomach aldehyde dehydrogenase in a group with more ordinary features.
The effects of substrates, products and other ligands on the susceptibility of inositol monophosphatase to proteolysis by endoprotease lys‐C
Authors: Gee N.S. , Knowles M.R. , McAllister G. , Ragan C.I.
Published: July 2002

Inositol monophosphatase is cleaved by endoprotease lys‐C at a single site (Lys36—Ser37). The rate of proteolysis is greatly reduced in the presence of substrate (D,L‐Ins(I)P) and Mg2+, and less so in the presence of Pi and Mg2+, consistent with protection of the susceptible bond in the E—P or E·Pi states of the enzyme. Potentiation by Li+ of the protection afforded by a substrate analogue, 1S‐phosphoryloxy‐2R,4S‐dihydroxycyclohexane, and Mg2+ supports the idea that Li+ binds to the E—P state.
Cloning, overexpression, purification and crystallisation of ribosomal protein L9 from Bacillus stearothermophilus
Authors: Vorgias Constantin E. , Kingswell Adrian J. , Dauter Zbigniew , Wilson Keith S.
Published: July 2002

The cloning, sequencing and overexpression of the gene coding for Bacillus stearothermophilus ribosomal protein L9 is described. The sequence corresponds directly to that presented for the protein itself by classical methods, differing at only a few amino acid positions. The purification and crystallisation of the corresponding L9 protein is presented. The crystals are isomorphous to those described for L9 obtained by conventional methods.
New evidence suggests that the initial photoinduced cleavage of the D1‐protein may not occur near the PEST sequence
Authors: Barbato Roberto , Shipton Catherine A. , Giacometti Giorgio M. , Barber James
Published: July 2002

When isolated reaction centres of photosystem 2 from pea or wheat are exposed to photoinhibitory illumination in the presence of an electron acceptor, breakdown products of the D1‐protein are observed having molecular masses ranging from about 24 to 10 kDa. By using antibodies raised to the C‐terminal or N‐terminal portions of D1 it was shown that the major breakdown fragment of 24 kDa was derived from the C‐terminus. This conclusion was supported by phosphorylation studies and from the digestion pattern obtained by lysine specific endoprotease‐induced proteolysis. The complementary N‐terminal breakdown fragment was found to have an apparent molecular mass of 10 kDa. The implications of these data are discussed in terms of the possible relationship between the 24 kDa C‐terminal fragment and the 23.5 kDa breakdown fragment detected in vivo by Greenberg et al. [1987, EMBO J. 6, 2865–2869] and it is suggested, based on limited proteolysis using papain, that the latter may not be derived from the N‐terminus as previously thought but also originates from the C‐terminus.