bluuebunny/crossref_metadata_2025 huggingface dataset:
5α,6α‐Epoxy‐cholestan‐3β‐ol (cholesterol α‐oxide): A specific substrate for rat liver glutathione transferase B
Authors: Meyer David J. , Ketterer Brian
Published: July 2002

A semi‐micro assay was developed for the conjugation of 5α,6α‐epoxy‐cholestan‐3β‐ol (cholesterol α‐oxide) with glutathione. The soluble supernatant of rat liver homogenate catalysed the reaction at a rate of 0.2–0.5 pmol.min−1 .mg protein−1 with 4μM cholesterol α‐oxide, while the reaction in the presence of GSH alone was barely detectable. Enzymic activity in the soluble supernatant was due equally to the two forms of glutathione transferase B (∼100 pmol.min−.mg protein−1), glutathione transferases AA, A, C and E being unreactive. The activity of purified glutathione transferase B was about 5‐times that expected from the activity of the soluble supernatant. Complex enzyme kinetics were obtained suggestive of substrate inhibition.
The presence of alkali‐labile sites in DNA daughter chains of UV‐irradiated Escherichia coli
Authors: Slezáriková Viera , Sedliaková Milena
Published: July 2002

DNA newly synthesized in UV irradiated Escherichia coli B/r Hcr+ was 2 min pulse‐labeled at various periods, then denatured and analysed by sucrose gradient centrifugation either in neutral or in alkaline conditions. Data indicate that in DNA of damaged cells alkali‐labile sites are produced. In cells saturated with inducible proteins production of alkali‐labile sites disappears in ∼1 h. In the absence of inducible proteins production of alkali‐labile sites continues.
Adult forms of glycogenosis type II
Authors: Reuser A.J.J. , Kroos M.
Published: July 2002

The activity of acid α‐glucosidase in cultured fibroblasts from adult patients with the lysosomal storage disease glycogenosis type II is only 10% of normal. A normal activity per molecule is found for the mature as well as for the precursor form of acid α‐glucosidase in adult mutant fibroblasts. Excessive lysosomal breakdown of mature enzyme purified from mutant fibroblasts and taken up by acceptor cells does not occur. However, the NH4Cl‐stimulated secretion of a precursor form of acid α‐glucosidase by adult mutant fibroblasts is markedly reduced. The results are indicative of a defect during the production of acid α‐glucosidase.
Preparation and neutralization characteristics of an antibody to the factor inducing differentiation of mouse myeloid leukemic cells
Authors: Tomida M. , Yamamoto-Yamaguchi Y. , Hozumi M.
Published: July 2002

Mouse myeloid leukemic M1 cells can be induced to differentiate into macrophages and granulocytes in vitro by a protein inducer (D‐factor) in body fluids and conditioned media from various cells and tissues. Antiserum to D‐factor was prepared by immunizing a rabbit with D‐factor partially purified from conditioned medium of mouse L929 cells. At 1:20 dilution, the antiserum nearly completely suppressed the activities of various D‐factor preparations from mice and partially suppressed the activities of preparations from rats and hamsters. It did not cross‐react with factors stimulating colony formation of macrophages and granulocytes from normal bone marrow cells.
Interaction of homo‐aza‐steroidal ester of [p‐[bis‐(2‐chloroethyl) amino]phenyl]acetic acid (ASE) with DNA of Ehrlich ascites tumor cells
Authors: Papageorgiou A. , Ivanov I.G. , Markov G.G. , Koliais S.I. , Boutis L. , Catsoulakos P.
Published: July 2002

A cytostatic, homo‐aza‐steroidal ester of [p‐[bis‐(2‐chloroethyl) amino]phenyl]acetic acid (ASE) was reduced with NaB3H4 and [3H]ASE‐treated DNA prepared in vitro. We found that: (1) ASE reacts preferentially with purines; (2) ASE decreases the thermal stability of the double helix upon binding to DNA; (3) [3H]ASE binding sites are clustered along the DNA molecules; (4) ASE binding sites probably represent oligo‐ or polypurine sequences.
A single‐step procedure for the isolation of individual mRNA species from crude lysates of Physarum polycephalum
Authors: Cox Robert A. , Smulian Nadia J.
Published: July 2002

An individual mRNA species was isolated directly from lysates of Physarum polycephalum by hybridization to immobilised complementary DNA. The solvent for lysis was a 6 M‐guanidinium salt solution, and the hybridization reaction was carried out at 42°C in 4 M guanidinium salt/33% (v/v) formamide buffer. The mRNA species isolated by this procedure was active in cell‐free protein synthesis and directed the synthesis of a polypeptide of M
r 25 500 ± 750.
Reconstitution of photosynthetic electron transfer in cyanobacterial heterocyst membranes
Authors: Hawkesford Malcolm J. , Houchins Jeffrey P. , Hind Geoffrey
Published: July 2002

Photosynthetic membranes have been isolated from heterocysts of the cyanobacterium Anabaena 7120. Electron transfer reactions associated with photosystem I have been investigated using single turnover flashes. Turnover rates, which were dependent on reconstitution with cytochrome c‐553 or plastocyanin, were maximal when a suitable electron donor system was provided. Hydrogen (via an endogenous uptake hydrogenase), NADH (via a dehydrogenase) or the ascorbate/dichlorophenolindophenol couple were all effective donors. NADPH could also serve as a donor but this system was dependent on addition of ferredoxin and ferredoxin—NADP reductase. Turnovers of P700, soluble cytochrome c‐553 and cytochrome b‐563 could be demonstrated.
Modification of histidine residues by diethyl pyrocarbonate leads to inactivation of the Rhodospirillum rubrum RrF1‐ATPase
Authors: Khananshvili Daniel , Zippora Gromet-Elhanan
Published: July 2002

The RrF1‐ATPase from the photosynthetic bacterium Rhodospirillum rubrum was rapidly and completely inactivated by diethyl pyrocarbonate (DEPC) at pH 6.0 and 22°C. When applied in 1 step 5 mM DEPC were required for > 90% inactivation and this DEPC‐modified enzyme showed an increase in absorption at 242 nm as well as a decrease in absorption at 280 nm, suggesting modification of both histidine and tyrosine residues. Complete inactivation of the RrF1‐ATPase could be obtained with only 250 μM DEPC when applied in 5 separate steps of 50 μM each. The only absorption change observed under these conditions was an increase at 242 nm indicating that the inactivation can be correlated with modification of histidine residues. Complete inactivation requires the modification of 2–3 histidine residues per molecule of RrF1.
Resonance Raman study on pentacoordinated and hexacoordinated ferrous nitrosyl myoglobin
Authors: Mackin H.C. , Benko B. , Yu N.-T. , Gersonde K.
Published: July 2002

The resonance Raman (RR) spectra of the hexacoordinated ferrous nitrosyl sperm whale myoglobin are independent of pH for both the 200–700 cm and 1350–1650 cm−1 regions. In agreement with earlier ESR [Eur. J. Biochem. (1972) 31, 578–584] and contrary to recent RR [Biochemistry (1982) 21, 6989–6995] results the RR spectra do not indicate a transition to the pentacoordinated ferrous nitrosyl derivative at low pH. However, interaction of the protein with sodium dodecylsulfate, leads to the formation of a pure pentacoordinated state with a typical RR spectrum. Replacement of 14NO for 15NO in this pentacoordinated ferrous nitrosyl derivative does not exhibit isotope effects using 413.1 excitation.
Chemical crosslinking of histone H1° to histone neighbours in nuclei and chromatin
Authors: Dashkevich Viktor K. , Nikolaev Lev G. , Zlatanova Jordanka J. , Glotov Boris O. , Severin Evgenii S.
Published: July 2002

Crosslinking of histones in mouse liver nuclei and extended chromatin with a bifunctional reagent leads to the formation of H1H1° heterodimers as well as H1°H1° homodimers. H1° can be also crosslinked to the core histones. Thus, the location of histone H1° within the basic repeating chromatin structure seems to be analogous to that of H1 histone.
Inhibition of the elongation step of protein synthesis by vaccinia virus
Authors: Tas P.W.L. , Martini O.H.W.
Published: July 2002

Vaccinia cores inhibit translation in cell‐free protein synthesis systems at two stages: initiation; and, as shown here, elongation. The former effect tends to obscure the latter. Elongation control could, however, be revealed as follows: when, in a reticulocyte of L‐cell lysate, initiation was blocked by a drug (edein), the residual [35S]methionine incorporation was severely reduced by the subsequent addition of vaccinia cores. The elongation block could also be demonstrated by analysis of ribosome profiles: treatment with edein alone permitted ribosomal run‐off; treatment with either the elongation inhibition anisomycin or with cores preserved the polyribosomes.
Primary sequence of the 5′‐terminal region of mouse 18 S rRNA and adjacent spacer
Authors: Raynal F. , Michot B. , Bachellerie J.P.
Published: July 2002

Among the stepwise cleavage reactions involved in the processing of rRNA precursors in mammalian cells, an early event corresponds to the removal of the so‐called ‘external transcribed regions’ which are located upstream 18 S rRNA sequence within the primary transcript. We have determined the primary sequence of the domain of mouse pre‐rRNA which encompasses this early processing site and analyzed its structural features with reference to the other eukaryotic homologs available. The potential involvement of secondary structure features of rRNA precursors in the recognition process for cleavage is discussed.
The 5′‐terminal sequence of TMV RNA question on the polymorphism found in vulgare strain
Authors: Meshi Tetsuo , Ishikawa Masayuki , Takamatsu Nobuhiko , Ohno Takeshi , Okada Yoshimi
Published: July 2002

The complete nucleotide sequence of TMV RNA (common strain) reported in [Proc. Natl. Acad. Sci. USA (1982) 79, 5818] its 5′‐end to be represented by two variants which differed in length. We have tested that result and sequenced the 5′‐terminal regions of two strains of TMV RNA (common strain OM and tomato strain L) using cloned cDNA copies. The results showed that the 5′‐terminal region of the TMV genome is not polymorphic and that one of the two variants cited above represents a tomato strain but not the common strain.
Transport of sugars or amino acids increases potassium efflux from isolated enterocytes
Authors: Brown P.D. , Burton K.A. , Sepúlveda F.V.
Published: July 2002

The increase is related to the transport of the non‐electrolyte, but not to volume regulatory events.
Induced changes in the affinity of 1,25‐dihydroxyvitamin D3 receptors in chick intestine
Authors: Bar Arie , Rosenberg Jacob , Hurwitz Shmuel
Published: July 2002

The contents of 1,25‐dihydroxyvitamin D3 (1,25(OH)2D3) in plasma and intestinal mucose were increased by dietary calcium and by dietary phosphorus restriction. The concentration of intestinal occupied receptors for 1,25(OH)2D3 was higher in calcium‐restricted birds. The affinity (association constant) of intestinal receptors for 1,25(OH)2D3 was lower in phosphorus‐restricted chicks, as compared to control or calcium‐restricted chicks. The number of binding sites were not influenced by dietary calcium or phosphorus restriction.
Three sequence‐specific endonucleases from Escherichia coli RFL47
Authors: Janulaitis A. , Petrušyté M. , Butkus V.
Published: July 2002

The characterization of the new restriction enzyme Eco47III recognizing a hexanucleotide palindromic sequence 5'AGC↓GCT and cleaving, as indicated by the arrow, is reported. It was isolated from Escherichia coli strain RFL47. Another two specific endonuclease Eco47I (isoschizomer of AvaII) and Eco47II (isoschizomer of AsuI) were also found in this strain. There are two Eco47III recognition sites on λ DNA at 20997 and 37060 basepairs. The central Eco47III fragment can be replaced by a cloned fragment in λ vector mutant in t
R2 gene; i.e., λ gt
The absence of the long 3'‐non‐translated region in mRNA coding for eye lens αA2‐crystallin of the frog (Rana temporaria)
Authors: Tomarev Stanislav I. , Zinovieva Rina D. , Dolgilevich Svetlana M. , Krayev Alexander S. , Skryabin Konstantin G. , Gause Georgyi G.
Published: July 2002

The nucleotide sequence of a cloned cDNA (clone pRt(1)297; GENE (1982) 17, 131) coding for a 18 kDa polypeptide of the frog eye lens has been determined. The sequence, 791 nucleotide in length has only one long open reading frame (447 nucleotides). The derived amino acid sequence in this frame has > 90% homology with the region 25–173 of αA2‐crystallin amino acid sequence from a related frog species Rana pipiens. The 5'‐terminal part of mRNA corresponding to the first 24 amino acids of αA2‐crystallin has been lost in cloning and substituted by an artefactual sequence. The 3'‐terminal part appears to be intact as follows from the presence of the universal poly(A) addition site and poly(A) tract. The 3'‐nontranslated region present in frog αA2‐crystallin mRNA (130 nucleotides) is about 4‐times shorter than in mammalian αA2‐crystallin mRNA. Intact αA2‐crystallin mRNA with a size of about 700 nucleotides as determined by Northern blot hybridization is about twice smaller than corresponding mammalian mRNAs.
Physical properties of ribosomal proteins isolated under different conditions from the Escherichia coli 50 S subunit
Authors: Tumanova L.G. , Gongadze G.M. , Venyaminov S.Yu. , Gudkov A.T. , Bushuev V.N.
Published: July 2002

Physical properties of ribosomal proteins obtained with or without denaturating agents were compared. CD measurements and NMR studies have shown that proteins L2, L19, L24 and L30 isolated under denaturing conditions have the same properties as those prepared avoiding denaturating agents. CD and NMR spectra of proteins L1, L6, L11, L23, L25 and L29 obtained by us under denaturating conditions practically coincide with the data for the same proteins reported under ‘mild’ conditions. These findings suggest that the differences of reported physical properties can be due to different procedures of protein renaturation rather than to the methods of their isolation.
Mapping of binding sites for Mu repressor and ner product within the left‐end EcoRI. C fragment of the Mu genome
Authors: Barlach Sabine , Schumann Wolfgang
Published: July 2002

Bacterial cells containing the ner gene of phage Mu inserted into pBR322 express a binding activity with specificity for the left‐end EcoRI. C fragment of Mu DNA. Crude extracts containing either Mu repressor or ner protein have been used to localize binding sites on TaqI subfragments of the EcoRI. C fragment. There are at least 3 distinct binding sites for the Mu repressor and 1 binding site for the ner protein on the EcoRI. C fragment. The possible biological function of these binding sites is discussed.
Heterogeneous turnover of terminal and core sugars within the carbohydrate chain of dipeptidylaminopeptidase IV isolated from rat liver plasma membrane
Authors: Volk Brigitte A. , Kreisel Wolfgang , Köttgen Eckart , Gerok Wolfgang , Reutter Werner
Published: July 2002

Dipeptidylaminopeptidase IV, a plasma membrane‐bound glycoprotein, is characterized by an intramolecular hetereneous turover of the protein backbone and carbohydrate chain. The faster turnover of the latter is restricted only to the outer sugars. The inner core sugars D‐mannose and N‐acetyl‐D‐glucosamine turn over at the same rate as the protein backbone
α2 High molecular mass cysteine proteinase inhibitor: HMrα2‐CPI
Authors: Pagano M. , Engler R.
Published: July 2002

HMrα2CPI was found to be an inhibitor of human liver cathepsin H by the measurement of the dissociation constant (K
i), the association rate constant (k
1) and the dissociation rate constant (k
−1) between the enzyme and the inhibitor. These data suggest that this protein‐proteinase inhibitor can play a physiological role in the regulation of free cathepsin H.
ATP‐dependent proteolysis in pea chloroplasts
Authors: Xiang-Qin Liu , Jagendorf Andre T.
Published: July 2002

Proteins newly formed from labeled amino acids by isolated intact pea chloroplasts are not entirely stable. Between 20 and 35% of the labeled protein is degraded over a 20–30 min incubation period in pulse‐chase experiments. Protein degration is prevented when chloroplast ATP level drops, as in the dark without added ATP. Degration is stimulated by adding ATP directly or by generating it in photophosphorylation. Susceptible new proteins are not stabilized against further additions of ATP, during incubation under ATP‐deficient conditions.
Effect of heme on the activity of chick embryo liver mitochondrial δ‐aminolevulinate synthase
Authors: Pirola B.A. , Srivastava G. , Borthwick I.A. , Brooker J.D. , May B.K. , Elliott W.H.
Published: July 2002

We have examined the effect of heme on the activity of native δ‐aminolevulinate synthase isolated from drug‐induced chick embryo liver mitochondria. The enzyme was not inhibited by concentrations of heme up to 1nM and this finding makes it improbable that heme acts physiologically to control mitochondrial δ‐aminolevulinate synthase activity.
Nucleotide sequence of the 5 S rRNA gene and flanking regions in the cyanobacterium, Anacystis nidulans
Authors: Douglas Susan E. , Doolittle W.F.
Published: July 2002

The nucleotide sequence of the 5 S rRNA gene and flanking regions (including the terminal 232 nucleotides of the 23 S rRNA gene) of Anacystis nidulans has been determined. The spacer between the 23 S and 5 S rRNAs is 70 nucleotides long and contains no detectable transcription termination or initiation signals similar to those found in the comparable region of plastid genomes. A stable stem‐and‐loop structure can be formed 16 nucleotides downstream from the 5 S rRNA gene, and this is probably the transcription termination signal for the rRNA gene cluster. Homologies between cyanobacterial and plastid genes have been calculated and their evolutionary significance discussed.
Phalloidin depletes the mitochondrial Ca2+ compartment of hepatocytes
Authors: Faulstich Heinz , Münter Klaus , Mayer D.
Published: July 2002

In 3 h of incubation, primary cultures of rat hepatocytes attach to the substratum and exchange about 2.2 nmol 45Ca2+ per mg protein. In the presence of 1 μM phalloidin, the exchanged amount of 45Ca2+ was found to be decreased by about 30%. Using the uncoupling agent FCCP and the ionophore A23187 for further characterisation we determined that the 45Ca2+ deficit caused by phalloidin occurs in the FCCP‐sensitive compartment, i.e., the mitochondria.
Extraction of SV40 T‐antigen from lysates of transformed cells
Authors: Lenstra J.A. , Smits R.A.M.M. , Bloemendal H.
Published: July 2002

Subcellular fractions from SV‐40 transformed hamster lens cells, prepared by chemical extractions, were tested for the presence of T‐antigen by immunoautoradiography. Most of the T‐antigen was present in the nucleus and was resistant to extraction by 2 M NaCl, indicating an association with the nuclear matrix. Another part of the T‐antigen was, under certain conditions, resistant to extraction of the cells with a nonionic detergent. This T‐antigen could be solubilized by Ca2+ at low temperature, conditions that also cause a specific depolymerization of microtubules.
Fructose 2,6‐biphosphate, sugar phosphates and adenine nucleotides in the regulation of glucose metabolism in the lactating rat mammary gland
Authors: Sochor Milena , Greenbaum A.L. , McLean Patricia
Published: July 2002

Fructose 2,6‐bisphosphate is present in the rat mammary gland, rising from a value of 1.4 nmol/g in pregnancy to 4.3 nmol/g tissue at 14 days lactation; the equivalent values calculated/ml intracellular water are 5.2 and 11.6 nmol, respectively. The tissue content of fructose 6‐phosphate, fructose 1,6‐bisphosphate, ATP and phosphoenolpyruvate remain relatively constant in the transition from pregnancy to the height of lactation. The changes in AMP, cyclic AMP, and citrate content of the mammary gland during lactation are such as to promote an increase in frutose 2,6‐bisphosphate formation and flux through phosphofructokinase.
Dolichol induces membrane leakage of liposomes composed of phosphatidylethanolamine and phosphatidylcholine
Authors: Lai Ching-San , Schutzbach John S.
Published: July 2002

Dolichol promotes the leakage of membranes in liposomes composed ofphosphatidylethanolamine and phosphatidylcholine but not liposomes composed only of phosphatidylcholine. The membrane leakage was assayed by measuring the entrapment of TEMPOcholine, a cationic spin probe, in liposomes using ESR methods. The percent of membrane leakage induced by dolichol was found to be linearly proportional to the concentrations of dolichol. It is proposed that dolichol enhances the formation of non‐bilayer configurations in liposomes containing phosphatidylethanolamine, thereby inducing membrane leakage.
Opposite and mutually incompatible structural requirements of type‐2 casein kinase and cAMP‐dependent protein kinase as visualized with synthetic peptide substrates
Authors: Pinna Lorenzo A. , Meggio Flavio , Marchiori Ferdinando , Borin Gianfranco
Published: July 2002

The synthetic hexapeptide Ser‐Glu‐Glu‐Glu‐Val‐Glu and its N‐acetylated derivative are readily and specifically phosphorylated by rat liver casein kinase TS (type‐2), while the derived heptapeptide with an additional N‐terminal Arg is a very poor substrate. Conversely, the substitution of Glu for Val5 in the synthetic peptide Arg‐Arg‐Ser‐Thr‐Val‐Ala, which is a good substrate for cAMP‐dependent protein kinase by virtue of the N‐terminal arginyl residues, prevents its phosphorylation by this enzyme. These data indicate that the site specificities of these two classes of protein kinases, requiring acidic and basic residues on the C‐and N‐terminal sides of the target residue(s), respectively, are mutually incompatible.
The gene coding for lipoprotein signal peptidase (lspA) and that for isoleucyl‐tRNA synthetase (ileS) constitute a cotranscriptional unit in Escherichia coli
Authors: Yamada Hisami , Kitagawa Masanari , Kawakami Makoto , Mizushima Shoji
Published: July 2002

The lspA gene coding for lipoprotein signal peptidase is located very close to the ileS gene coding for isoleucyl‐tRNA synthetase on the Escherichia coli chromosome. Deletions were generated in vitro from both ends of the 4.3 kb fragment that carries the lspA gene and the ileS gene, and the expression of the two genes was examined before and after insertion of the trp promoter‐operator at one end. The results indicate that the lspAandileS genes constitute a cotranscriptional unit in the order of promoter‐ileS‐lspA. The gene order of dnaJ‐rpsT‐ileS‐lspA‐dapB around 0.5 min on the E. coli chromosome map was also determined.
Sex‐ and tissue‐specific, but hormonally independent, demethylation at the 3'‐end of Xenopus vitellogenin gene B1
Authors: Ng Wee Chit , Baker Betty S. , Tata Jamshed R.
Published: July 2002

We describe three HpaII‐specifying sequences in 6 kbp of DNA at the 3'‐end of Xenopus vitellogenin gene B1 (two within the coding sequence and one downstream) which remain methylated in all tissues of adult male Xenopus. These sites are however fully demethylated exclusively in adult female Xenopus liver parenchymal cells but not in oviduct, kidney or erythrocytes. Developmental studies suggest that this tissue‐ and sex‐specific demethylation may occur gradually after metamorphosis. The methylation of these 3'‐sites is independent of transcriptional activation by oestrogen of vitellogenin genes in male or female Xenopus.
Comparison of carotenoid and bacteriochlorophyll calibrations of the membrane potential in chromatophores of Rhodopseudomonas capsulata
Authors: Symons Marc , Sybesma Christiaan
Published: July 2002

An extensive comparison of bacteriochlorophyll and carotenoid absorbance changes shows that, under optimal conditions, these two intrinsic probes yield essentially the same value for the light‐induced membrane potential. The bacteriochlorophyll changes appear to be more sensitive to ageing than the carotenoids. The effect of prolonged sonication on the diffusion potential‐induced bacteriochlorophyll and the carotenoid changes suggests that this treatment decreases the effective thickness of the membrane.
Interactions between cro repressor and the model specific binding site
Authors: Kirpichnikov M.P. , Kurochkin A.V. , Chernov B.K. , Skryabin K.G.
Published: July 2002

Binding of λ phage cro repressor to the synthetic half of OR3, the most conservative half of the specific binding sites, was investigated by proton nuclear magnetic resonance spectroscopy. It was found that the α‐helical segment (27–36) of the protein was involved in specific interactions with the model binding site. The 3‐dimensional structure of cro repressor does not change noticeably upon complex formation. Intercalation can be excluded as a possible means of interaction.
The combined use of selective deuteration and double resonance experiments in assigning the 1H resonances of valine and tyrosine residues of dihydrofolate reductase
Authors: Birdsall B. , Feeney J. , Griffiths D.V. , Hammond S. , Kimber B. , King R.W. , Roberts G.C.K. , Searle M.
Published: July 2002

Selective deuteration is a general solution to the resolution problem which limits the application of double resonance experiments to the assignment of the 1H NMR spectra of proteins. Spin‐decoupling and NOE experiments have been carried out on Lactobacillus casei dihydrofolate reductase and on selectively deuterated derivatives of the enzyme containing either [γ‐2H6]Val or (α,δ2,ϵ1‐2H3]His, [α,δ1,δ2,ϵ1,ϵ2,ζ‐2H6]Phe, [α,δ1,ϵ3,ζ2,ζ3,η2‐2H6]Trp and [α,ϵ1,ϵ2‐2H3]Tyr. When combined with ring‐current shift calculations based on the crystal structure of the enzyme, these experiments allow us to assign 1H resonances of Val 61, Val 115, Tyr 46 and Tyr 68.
NAD+ kinase: molecular weight determination by low‐angle laser‐light scattering
Authors: Gabriel Mina K. , McGuinness Eugene T.
Published: July 2002

Low‐angle laser‐light scattering (LALLS) was employed to measure the absolute molecular weight of chicken liver NAD+ kinase (NADK). The weight‐average molecular weight (
w,) was found to be 275000 ± 15000. The corresponding value for the second virial coefficient was −1.65 × 10−3 ml·mol·g2. The value for M
w is in close accord with estimates reported for pigeon liver (270000) and C. utilis (260000) NADK. If the active enzyme is a dimer, the weight difference between pigeon/chicken liver and rabbit liver (136000) NADK would indicate that the latter enzyme is an active monomer unit.
Chloroplastic glutamine synthetase from tobacco leaves: a glycosylated protein
Authors: Nato Farida , Hirel Bartrand , Nato Aimé , Gadal Pierre
Published: July 2002

The amino acid and carbohydrate content of chloroplastic glutamine synthetase from tobacco leaves has been analysed. The enzyme subunit contanins 5% carbohydrate, mainly represented by glucosamine, galactosamine, glucose, galactose and mannose residues. The enzyme subunit displayed a single band of molecular mass 44000 Da after sodium dodecyl sulphate (SDS) electrophoresis. However, when isoelectrofocussing electrophoresis was performed, four subunits were evident differing by their charge. Furthermore, the four different subunits stained positively when tested with periodic acid Shiff reagent, showing that sugars and amino sugars were present within all the subunits.
Organ‐specific properties of cytochromes P‐450s21 (steroid 21‐hydroxylases) of liver and adrenocortical microsomes
Authors: Ichikawa Yoshiyuki , Hiwatashi Atsuo , Tsubaki Motonari
Published: July 2002

Organ specificities of cytochrome P‐450s21 (steroid 21‐hydroxylase) were investigated. The substrate specificity of the liver cytochrome P‐450s21 was found to be different from that of adrenocortical cytochrome P‐450s21. The steroid 21‐hydroxylase activity of liver microsomes decreased with treatment by sodium phenobarbital or β‐naphthoflavone and was inhibited by anti‐cytochrome b
5 immunoglobulin, although that of adrenocortical microsomes was not. The liver cytochrome P‐450s21 was immunochemically similar to adrenocortial cytochrome P‐450s21. The bovine liver and adrenocortical cytochromes P‐450s21 showed immunoprecipitin lines against antibody to bovine adrenocortical cytochrome P‐450s21. The molecular masses of the bovine liver and adrenocortical cytochromes P‐450s21 were 60 ± 1 and 50 ± 1 kDa, respectively. The content of cytochrome P‐450s21 and its percentage for the total microsomal cytochrome P‐450 were immunochemically determined using the antibody to the bovine adrenocortical cytochrome P‐450s21.
Coupling between phosphatidylinositol metabolism and cdc 28 gene product of Saccharomyces cerevisiae
Authors: Dudani Anil Kumar , Prasad Rajendra
Published: July 2002

It was shown that the decrease in phosphatidylinositol (PI) content in cdc 28 G1‐cells was due to a defect in inositol transport. This decrease in inositol transport was linked to microtubular function which was evident by the effect of a microtubular disrupting agent (colcemid) on inositol transport in stationary phase A364A cells. The involvement of PI in yeast G1 phase was further substantiated by the observation that o‐phenanthroline, which blocks yeast cells in G1 phase, could inhibit inositol transport and PI levels as well. It is proposed that the regulation of PI metabolism is mediated by the gene cdc 28 and that microtubules may play a major role in the mechanism of action of this gene product.
Yeast 6‐phosphofructo‐2‐kinase
Authors: Yamashoji Shiro , Hess Benno
Published: July 2002

Yeast 6‐phosphofructo‐2‐kinase (PFK2) was purified about 4000‐fold by CM‐Sephadex and Blue Sepharose chromatographies. Yeast contained two kinds of PFK2, both with apparent M
r values of 250 000 as estimated by gel filtration. The apparent K
m values of the major components for fructose 6‐phosphate (F6P) and ATP were estimated as 0.5 and 0.7 mM, respectively.
Mare lactotransferrin: purification, analysis and N‐terminal sequence determination
Authors: Jollès Jacqueline , Donda Alenka , Amiguet Patrick , Joliès Pierre
Published: July 2002

Mare lactotransferrin has been purified and analyzed. Its molecular mass is 81 kDa. A 28 amino acid long N‐terminal sequence was established and a first series of comparisons with other transferrins was performed.
Induction of rat α2‐macroglobulin in vivo and in hepatocyte primary cultures: synergistic action of glucocorticoids and a Kupffer cell‐derived factor
Authors: Bauer Joachim , Birmelin Manfred , Northoff Gerd-Hinrich , Northemann Wolgang , Tran-Thi Thuy-Anh , Ueberberg Heinz , Decker Karl , Heinrich Peter C.
Published: July 2002

Turpentine injection into rats elicits enhanced secretion of acute phase proteins inducing α2‐macroglobulin (α2M). Hypophysectomized rats, however, do not respond in this way unless dexamethasone is given together with turpentine. On the other hand, dexamethasone injection alone did not result in an induction of α2M synthesis. When a medium of Kupffer cell cultures was added to hepatocytes, a dose‐dependent stimulation of α2M synthesis of up to 4‐fold after 10–12 h was observed. However, the presence of low concentrations (10−9 M) of dexamethasone was essential for the stimulatory effect. We conclude that the acute phase induction of α2M in hepatocytes requires the synergistic action of glucocorticoids and a non‐dialysable factor secreted by Kupffer cells.
Purification and characterization of a hormone‐like factor which inhibits cholera secretion
Authors: Lönnroth I. , Lange S.
Published: July 2002

A factor which inhibits intestinal hypersecretion induced by cholera toxin was studied. The factor was extracted from intestinal mucosa or pituitary gland of pig. It has an isoelectric point of pH 4.7 ± 0.1 at 10° C and showed a weak affinity to dextran gel and a strong affinity to agarose gel. From agarose gel the factor was eluted with high concentrations of D‐galactose or α‐methyl‐D‐glucose, while D‐glucose and lactose were less effective. After purification more than 2000 times by isoelectric focusing and gel chromatography, the factor was shown by SDS‐polyacrylamide gel electrophoresis to be a protein consisting of subunits of molecular mass 30, 17 and possibly 15 kDa.
Uroporphyria development in cultured chick embryo fibroblasts long‐term treated with chloramphenicol and ethidium bromide
Authors: de Muys Jean-Marc , Morais Réjean
Published: July 2002

Long‐term chloramphenicol‐ and ethidium bromide‐treated chick embryo fibroblasts synthesize large amounts of porphyrins from exogenously added σ‐aminolevulinic acid. The porphyrins consist mainly of uro‐ and heptacarboxyporphyrins and are retained within cells. Uroporphyria development is a time‐dependent process which accompanies a step‐wise decrease in the capacity of the mitochondrial respiratory chain. Upon removal of chloramphenicol from the medium, the pattern of porphyrin production readily returns to normal (mainly proto‐ and coproporphyrins found in the medium) while ethidium bromide‐treated cells remain uroporphyric. The results suggest that impairment of mitochondrial functions in chicken by xenobiotics leads to uroporphyria development.
Structural organization of photosystem I reaction centers
Authors: Karapetyan N.V. , Shubin V.V. , Rakhimberdieva M.G. , Vashchenko R.G. , Bolychevtseva Yu.V.
Published: July 2002

Using a phosphoroscopic attachment to the dichrograph, light‐induced circular dichroism spectra have been measured for chlorophyll‐protein complexes of Photosystem I. Minor components at 672, 678 and 685 nm are observed in these spectra in addition to the components of dimer splitting of the P700 Qy transition at 691 and 698 nm. The minor components are due to the Chl672, Chl678 and Chl685 forms of antenna chlorophylls, the optical activity of which is changed 2–4% as a result of P700 oxidation. It is suggested that P700 is not an isolated dimer but that it is included in a local complex comprising 8–10 chlorophyll molecules with an exciton level splitting value of 120–140 cm−1.
The effect of aminoacyl‐ or peptidyl‐tRNA at the A‐site on the arrangement of deacylated tRNA at the ribosomal P‐site
Authors: Babkina G.T. , Bausk E.V. , Graifer D.M. , Karpova G.G. , Matasova N.B.
Published: July 2002

Photoreactive derivatives of E. coli tRNAPhe bearing arylazido groups on guanine residues (azido‐tRNA) were used for affinity labelling of E. coli ribosomes in the region of the P‐site when the A‐site was either free or occupied by aminoacyl‐ or peptidyl‐tRNA. Corresponding complexes of azido‐tRNA with ribosomes and poly(U) were obtained both nonenzymatically and with the use of elongation factors. UV‐irradiation of the complexes resulted in labelling of ribosomal proteins (preferentially of 30 S subunit). Proteins S9 and S21 were labelled only when the A‐site was free; S14 — only when it was occupied; S11, S13, S19 — in both cases; S5, S7, S12, S20 — in some states.
Distribution of non‐enzymatically bound glucose in in vivo and in vitro glycosylated type I collagen molecules
Authors: Le Pape Alain , Guitton Jean-Dominique , Muh Jean-Pierre
Published: July 2002

Non‐enzymatic glycosylation of collagen occurs both in vivo during diabetes and in vitro after incubation with glucose. Glycosylated collagen exhibits altered physicochemical and biological properties which could explain some of the complications of diabetes. To provide a mechanistic explanation of this modification the localization of bound glucose was investigated using NaB[3H]H4 reduction and CNBr cleavage. Glucose fixation is distributed mainly on the α1CB6 peptide after in vitro glycosylation whereas this distribution occurs less specifically during diabetes. It is concluded that fibrillogenesis alteration of in vitro glycosylated collagen is related to glucose fixation on free ϵNH2 sites normally implied in intermolecular interactions.
Inorganic phosphate‐enhanced ADP release on the chloroplast coupling factor
Authors: Komatsu-Takaki Mizuho
Published: July 2002

The effect of Pi on the release of tightly bound ADP on the spinach chloroplast coupling factor was studied. Pi enhanced the release of tightly bound ADP in the dark with a half maximal effect at 2 mM. The pH optimum of the Pi‐enhanced ADP release was above 8.0. The Pi‐enhanced ADP release was above 8.0. The Pi‐enhanced ADP release occurred on the same site as the light‐enhanced ADP release. Pi and light‐dependently bound ADP underwent no Pi‐enhanced release in the following dark. This shows that the site on which Pi‐enhanced ADP release occurs differs from the site on which Pi‐dependent ADP binding occurs.
Molecular cloning and restriction mapping of a Simian virus 40 deletion mutant derived from Simian transformants expressing a non‐karyophilic T antigen
Authors: Fantuzzi Lia Fischer , Vesco Cesare
Published: July 2002

A replication‐defective Simian virus 40 genome, with a deletion of about 120 nucleotides in the region encoding the N‐terminal fourth of the large T antigen, has been isolated from the DNA of Simian cells transformed by SV40. Both the original transformation, and the murine transformants obtained by transfection with this cloned mutant DNA, produced a large T antigen displaying in immunofluorescence an exclusively cytoplasmic localization. The protein apparent molecular mass (83 kDa) was about 6% smaller than that of normal karyophilic large T. Restriction analysis showed that the deletion eliminated two close HinfI sites, at nucleotides 4459 and 4376 (map unit 0.50).
Specific transcription of Orthopox virus DNA by HeLa cell RNA polymerase II
Authors: Archard L.C. , Johnson K. , Malcolm A.D.B.
Published: July 2002

A HeLa cell extract was used to transcribe DNA isolated from cowpox virus. Truncated templates generate accurately initiated run‐off transcripts of discrete sizes and whose sensitivity to inhibition by α‐amanitin indicates synthesis by cell RNA polymerase II. A mapped restriction fragment of wild‐type cowpox DNA contains specific sites of initiation which are not detected in the geographically equivalent fragment from a cowpox mutant having a defined sequence rearrangement in this region.
Azidocytidine is incorporated into RNA of 3T6 mouse fibroblasts
Authors: Åkerblom Lennart
Published: July 2002

Earlier work has shown that azidocytidine inhibits the growth and DNA synthesis of 3T6 mouse fibroblasts by inactivation of the enzyme ribonucleotide reductase. RNA synthesis, as measured by incorporation of [3H]cytidine was not affected. Here I show that azidocytidine is incorporated into RNA, but not into DNA. Incorporation of the analogue into RNA may under special circumstances contribute to the biological effect of the nucleoside.
Membrane‐bound N‐acetyl‐β‐glucosamimdase
Authors: Kato Goro , Suzuki Yoshiyuki
Published: July 2002

Several lysosomal enzymes solubilized at pH 4 from saponin‐treated membranes showed markedly variable affinities to the bovine liver phosphomannosyl receptor in both bovine and human livers. The enzymes from I‐cell disease liver did not bind the receptor in spite of normal intracellular activities. N‐Acetyl‐β‐glucos‐aminidase was effectively released from the membrane preparation of a control liver by mannose 6‐phosphate, and other sugars showed little effect in this experiment. However, in the I‐cell disease liver, dissociation occurred not by mannose 6‐phosphate but by other sugars, such as fucose, mannose and N‐acetyl‐D‐glucosamine. These results indicate the presence of an alternate transport system other than the pathway mediated by the mannose 6‐phosphate receptor, and the role of other sugar‐binding proteins is discussed in intracellular processing and transport of newly synthesized enzymes.
Pulse‐radiolysis study of daunorubicin redox cycles
Authors: Houée-Levin C. , Gardès-Albert M. , Ferradini C. , Faraggi M. , Klapper M.
Published: July 2002

Daunorubicin aqueous solutions were reduced by COO.−1 or eaq
−1 free radicals produced by pulse radiolysis. The kinetics of the semiquinone radical formation and decay were studied. The semiquinone disproportionation leads to a pseudo‐equilibrium between the drug, its semiquinone and hydroquinone reduced states (K
eq = 30 at pH 7), which lasts a few hunderd milliseconds and which is destroyed by the hydroquinone glycosidic cleavage. Consequences concerning daunorubicin antitumour action are briefly discussed.
Effects of prostaglandin E2 and cholera toxin on apical sodium uptake in thyroid epithelial cells: role of cAMP
Authors: Gerard Corinne , Verrier Bernard , Mauchamp Jean
Published: July 2002

When cultured in tissue culture polystyrene dishes, porcine thyroid cells formed polarized monolayers. Their apical pole was oriented towards the culture medium. Influx of sodium 22 (5 min) through the apical surface was partially inhibited by amiloride. Amiloride‐sensitive Na uptake was increased about 3‐fold by prostaglandin E2 (1 μM, 30 min) and by cholera toxin (0.01 , 1 h). This increase, which was also obtained with forskolin and 8‐(4‐chlorophenylthio)adenosine‐3':5'‐monophosphate, cyclic (8‐chloro‐cAMP), is probably a consequence of the increase of the intracellular cAMP level by prostaglandin and cholera toxin.
The vasoactive proteins in human urine
Authors: Giorginis S. , Dees C. , Peterknecht S.
Published: July 2002

We have purified vasoactive polypetides from the urine of normotensive humans by gel filtration on Sephadex G150 superfine ionic exchange chromatography on DEAE‐cellulose and isoelectric focusing in poly‐ acrylamide gels using a pharmalyte pH range of 2.5–5.0. The purified polypetide fraction yielded four bands by isoelectric focusing with isoelectric points at pH 4.15, 4.05, 3.9 and 3.8. On dodecyl sulphate/polyacryl‐ amide gel electrophoresis (page) two bands appeared, one small band with a Mr
of 29 000 and one broad band ranging from Mr
49 000 to Mr
42 500. The polypetides lower the blood pressure of rabbits in a bioassay and cleave D‐valyl‐L‐leucyl‐L‐arginine‐4‐nitroanilide with a specific activity comparable to that of kallikrein.
Demonstration of chondroitin sulfates degrading endo‐β‐glucuronidase activity in rabbit liver
Authors: Takagaki Keiichi , Nakamura Toshiya , Majima Mitsuo , Endo Masahiko
Published: July 2002

Reduced chondroitin sulfate was incubated with rabbit liver extracts followed by reduction once more with sodium [3H]borohydride, and then passed through a Sephadex G‐100 column. Chondroitin sulfate obtained from the incubation medium at pH 4 was only slightly depolymerized and was highly radioactive. Paper Chromatographic analyses showed that glucuronic acid residues became exposed at the reducing terminal of chondroitin sulfate after incubation with the liver extracts. These results suggest that endo‐β‐glucuronidase activity which degrades chondroitin sulfate is present in the rabbit liver.
Localization of a new proteolytic site accessible in oxidized myosin rod
Authors: Nyitray László , Mócz Gábor , Bálint Miklós
Published: July 2002

We have compared the proteolysis pattern of reduced and oxidized myosin rods in which the five pairs of SH‐groups were interchain crosslinked by employing CuCl2 or 5,5'‐dithiobis‐2‐nitrobenzoate. In the tryptic digest of oxidized rod three new fragments appeared on SDS‐polyacrylamide gel electrophoresis (chain masses of 100, 45, and 25 kDa). Based on the N‐terminal sequences of the isolated peptides, it is concluded that oxidation creates a new cleavage site 102 residues away from the N‐terminus of the rod, in the vicinity of one of the modified SH‐groups (Cys‐108). This observation indicates that S‐S crosslinking of myosin rod leads to a local unfolding of the coiled‐coil structure.
Aromatic ring cleavage in degradation of β‐O‐4 lignin substructure by Phanerochaete chrysosporium
Authors: Umezawa Toshiaki , Higuchi Takayoshi
Published: July 2002

The degradation of a β‐O‐4 lignin substructure model dimer, 4‐ethoxy‐3‐methoxyphenylglycerol‐β‐guaiacyl ether (I), by the white‐rot fungus Phanerochaete chrysosporium was investigated. The guaiacyl aromatic ring of the dimer (I) was first cleaved to give the cyclic carbonate of 4‐ethoxy‐3‐methoxyphenylglycerol (II) which was then converted to 4‐ethoxy‐3‐methoxyphenylglycerol (III). The carbonate carbon of (II) was found to be derived from the guaiacyl group of (I) based on tracer experiments with 13C.
Brain micro glutamic acid‐rich protein is the C‐terminal endpiece of the neurofilament 68‐kDa protein as determined by the primary sequence
Authors: Isobe Toshiaki , Okuyama Tsuneo
Published: July 2002

The amino acid sequence of bovine brain micro glutamic acid‐rich protein was determined by analysis of tryptic and Trimeresurus flavoviridis protease peptides of the molecule. The protein comprised 82 amino acid residues and has an M
r of 8992. The established sequence was highly homologous (90% identity) to the sequence of C‐terminal 82 residues of the neurofilament 68‐kDa protein from porcine spinal cord; there are differences of 8 residues which could be species‐specific amino acid substitutions. This indicates that the micro glutamic acid‐rich protein may arise by a restricted proteolysis of the neurofilament 68‐kDa protein, with the break occuring toward the C‐terminus.
Differential effects of the K+ channel blockers apamin and quinine on glucose‐induced electrical activity in pancreatic β‐cells from a strain of ob/ob (obese) mice
Authors: Rosario Luis M.
Published: July 2002

The effects of apamin and quinine on glucose‐induced electrical activity in pancreatic islets from ob/ob mice (Norwich colony) were compared. Apamin (40–400 nM) increased the duration of the bursts of electrical activity, whereas quinine (50–100 μM) affected only slightly the steady‐state electrical response to glucose. This sensitivity to apamin and poor response to quinine contrast with the resistance to apamin and sensitivity to quinine previously reported for pancreatic islets from albino mice. The results give further support to the idea that pancreatic β‐cells from ob/ob mice have a modified Ca2+‐activated K+ permeability.
Hemoglobin Roseau‐Pointe a Pitre α2β290 (F6) Glu → Gly: a new hemoglobin variant with slight instability and low oxygen affinity
Authors: Merault G. , Keclard L. , Saint-Martin C. , Jasmin K. , Campier A. , Delanoe-Garin J. , Arous N. , Fortune R. , Theodore M. , Seytor S. , Rosa J. , Blouquit Y. , Galacteros F.
Published: July 2002

A Dominican neonate carrying a new abnormal hemoglobin, hemoglobin Roseau Pointe‐à‐Pitre α2β290 (F6) Glu → Gly, was detected in Guadeloupe during application of a cord blood screening program. This variant behaved in isoelectrofocusing as an Hb D, and displayed instability and low whole blood oxygen affinity. In the affected family it was present, either isolated, or in association with a β+ thalassemia trait.
Regulation by thyrotropin of acyl‐CoA: cholesterol acyltransferase in cultured thyroid cells
Authors: Margotat Alain , Mauchamp Jean
Published: July 2002

ACAT activity measured in microsomes of thyroid cells cultured for 4 days in the presence of TSH (1 ) was two or three times lower than that of the control cells cultured for the same period in the absence of TSH. The pool of cellular cholesterol which served as the ACAT substrate, was not exchangeable with exogenous cholesterol provided in the form of liposomes. However, the incubation of microsomes with liposomes made it possible to increase the cholesterol content in the microsomes by 35%, and this resulted in the activation of ACAT activity. Nevertheless, maximum activity measured after activation in the microsomes of the control cells remained higher than that of the microsomes of cells cultured in the presence of TSH. These findings would suggest that TSH acted by diminishing the cellular content in ACAT enzyme, as well as modifying the distribution of cholesterol in the intracellular membranes.
B‐Z transition in poly(dG‐dC)·poly(dG‐dC) in the presence of formaldehyde amino derivatives
Authors: Poverenny A.M. , Kiseleva V.I. , Tyaglov B.V. , Permogorov V.I.
Published: July 2002

It was shown by circular dichroism that the B‐Z transition of poly(dG‐dC)·poly(dG‐dC) in high NaCl concentrations occurred more rapidly in the presence of formaldehyde and Tris. The product of formaldehyde and glycine interaction induces changes in the poly(dG‐dC)·poly(dG‐dC) CD spectral characteristics of a ‘B‐like’ conformation. It is supposed that the B‐Z transition occurs without large‐scale hydrogen bond breakage.