bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on the mechanism of the fluorescence decline induced by strong actinic light in PS II particles under different redox conditions
Authors: Renger G. , Koike H. , Yuasa M. , Inoue Y.
Published: July 2002

Fluorescence changes induced by strong actinic light at room temperature were measured in isolated photosystem II (PS II) particles under different redox conditions. Comparative measurements of the absorption changes accompanying the light‐induced fluorescence decay show that in the absence of Na2S2O4 the formation of a chlorophyll cation radical (probably together with oxidized carotenoid) causes a quenching while in the presence of Na2S2O4 photoaccumulation of the pheophytin anion radical (Pheo.−) takes place. The 695 nm band of the 77 K emission spectrum becomes specifically reduced if Pheo.− accumulates in the reaction center, whereas in the case of quenching by the cation radicals the ratio of the emission peaks at 685 nm and 695 nm remains constant. The present data favor the hypothesis that F‐695 originates from the PS II reaction center [FEBS Lett. (1982) 147, 16–20]. If the primary plastoquinone acceptor (PQA) stayed oxidized in the dark before the onset of the illumination. Pheo.− photoaccumulation was not observed. This effect is explained by the existence of at least one further redox component which is able to accept electrons efficiently from Pheo.−. The proposed model also explains the differences in the redox titration curves of the electrochromic bandshift and the inital fluorescence, respectively.
Purified glucocorticoid—receptor complexes from rat liver cytosol preferentially bind in vitro to a homologous DNA fraction whose transcription is activated by cortisol
Authors: Romanov George A. , Kuzmenko Alexander P. , Dashkevich Vera S. , Salganik Rudolf I. , Vanyushin Boris F.
Published: July 2002

The in vitro binding of 2000‐fold purified rat liver glucocorticoid—receptor complexes to functionally differing homologous DNA fractions has been studied. The effectiveness of receptor binding to the transcriptionally active DNA, isolated from rat liver 4 h after cortisol administration, increased by 1.6–1.8‐fold with simultaneous reduction in receptor affinity for the hardly extractable DNA fraction. The analogous DNA fractions from control animals did not differ in ability to bind the receptor. This suggests that sites of high affinity for the receptor are directly involved in the in vivo process of hormonal transcription activation.
The myoglobin of primates: the Night Monkey, Aotes trivirgatus (Cebidae, Platyrrhini, Anthropoidea)
Authors: Heinbokel Nils , Lehmann Hermann
Published: July 2002

The amino acid sequence of the myoglobin of the South American Night Monkey, Aotes trivirgatus, is identical to that of the marmoset (Callithrix jacchus [1]) except for residue 21 which is isoleucine in the marmoset, like in all other anthropoids, but valine in Aotes. Analysis of a possible pathway of the evolution of Aotes myoglobin using 18 known primate myoglobin sequences [2–5] supports the classification of the Night Monkey within Anthropoidea and Platyrrhini but it indicates that this species might be more closely related to the marmoset (family Callitrichidae) than to the family Cebidae as a member of which it is commonly classified.
erythro‐β‐hydroxyaspartic acid in bovine factor IX and factor X
Authors: Sugo Teruko , Fernlund Per , Stenflo Johan
Published: July 2002

To localize β‐hydroxyaspartic acid in factor IX and factor X the two proteins were cleaved with cyanogen bromide and trypsin, respectively. Peptides containing β‐hydroxyaspartic acid were isolated and subjected to Edman degradation. The phenylthiohydantoin derivative of β‐hydroxyaspartic acid was identified by HPLC in position 3 in the factor IX fragment and in position 1 in the factor X fragment. This corresponds to position 64 in factor IX and position 63 in the light chain of factor X. The assignments were confirmed by subtractive Edman degradation and with the dansyl method.
Protective effect of L‐carnitine on hyperammonemia
Authors: O'Connor José-Enrique , Costell Mercedes , Grisolía Santiago
Published: July 2002

Inborn errors of the urea cycle, liver malfunction and drug‐induced hepatotoxicity are causes of life‐threatening encephalopathies arising from hyperammonemia. L‐Carnitine prevented entirely ammonia toxicity in mice when injected intraperitoneally 30 min before a lethal dose of ammonium acetate. Survival depends on the dose of L‐carnitine injected, e.g., 0, 60, 70, 80 and 100% with 0, 1, 2, 8 and 16 mmol L‐carnitine/kg, respectively. At the highest doses L‐carnitine abolishes the convulsions that accompany acute ammonia intoxication. At lower doses it delayed their onset. The protective effect was associated with a marked decrease of blood ammonia, while in unprotected mice ammonemia was lethal in less than 15 min. When sustained hyperammonemia was induced by urease injections, protection was also obtained. The mechanism of protection is under investigation, however, since L‐carnitine facilitates fatty acid entry into mitochondria, possibly ATP or reducing equivalents are increased.
Inhibition of ribonuclease activity during RNA synthesis in isolated yeast nuclei by cadmium
Authors: Schulz-Harder Bernd , Thüroff Eduardo
Published: July 2002

We have developed an efficient transcription system in isolated yeast nuclei. If MnCl2 is substituted by CdCl2, degradation of newly synthesized RNA is markedly reduced. This effect is due to the inhibition of nuclear ribonuclease activity, since microsomal ribonuclease activity is less affected by the cation. The extent to which the addition of CdCl2 to the in vitro transcription assay inhibits ribonuclease activity is demonstrated by the measurements of the size of newly synthesized RNA. Efficient RNA synthesis in this system is not affected up to a concentration of 0.1 M CdCl2.
Mutant hemoglobin stability depends upon location and nature of single point mutation
Authors: Smith Michael L. , Hjortsberg Kerstin , Romeo Paul-Henri , Rosa Jean , Paul Karl-Gustav
Published: July 2002

The temperature dependence of the rates of heme release from the β subunits of methemoglobin A and 5 β mutant methemoglobins has been determined. The rates were largest fort wo hemoglobins with mutations distal to heme, previously known to be unstable. The other 3 mutants also released heme faster than A. These hemoglobins, with single point mutations at the α1β2 interface, were previously thought to be stable. The low reported yields of the 5 mutant protein covaries with the relative rates of heme release from the met species.
Hb Marseille [α2β2 N methionyl ‐ 2 (NA2) His → Pro]: a new β chain variant having an extended N‐terminus
Authors: Blouquit Y. , Arous N. , Lena D. , Delanoe-Garin J. , Lacombe C. , Bardakdjian J. , Vovan L. , Orsini A. , Rosa J. , Galacteros F.
Published: July 2002

A new abnormal hemoglobin was found in a diabetic Maltese woman by citrate agar electrophoresis. This variant was undetectable by isoelectric focusing. No hematological abnormalities were observed. The structural analysis included isolation of the abnormal β chain, high pressure liquid chromatography of the corresponding tryptic peptides and then microsequencing of the abnormal T1. These procedures revealed a double abnormality: the presence of a methionyl residue extending the NH2 terminus and a histidine to proline substitution in position NA2.
Epitopes of human intestinal alkaline phosphatases, defined by monoclonal antibodies
Authors: Ray Kunal , Vockley Jerry , Harris Harry
Published: July 2002

Antibody additivity assay
Topology
XANES study of iron displacement in the haem of myoglobin
Authors: Bianconi A. , Congiu-Castellano A. , Dell'Ariccia M. , Giovannelli A. , Durham P.J. , Burattini E. , Barteri M.
Published: July 2002

The XANES (X‐ray absorption near edge structure) spectra of deoxy human adult haemoglobin (HbA) and myoglobin (Mb) have been measured at the wiggler beam line of the Frascati synchrotron radiation facility. The XANES are interpreted by the multiple scattering cluster theory. The variations in the XANES between HbA and Mb are assigned to changes in the Fe‐porphyrin geometry.
Condensation of polynucleosome by histone H1 binding
Authors: Watanabe Fumiyuki
Published: July 2002

The cooperative binding of histone H1 to polynucleosome was studied quantitatively. The equilibrium and kinetic data were satisfactorily described in terms of the large ligand model. The binding constant K and the cooperativity parameter q showed remarkable salt effects: K = 7.5 × 107 M−1 and q = 1.3 × 104 at 0.2 M NaCl, pH 7.5 and 20°C. This considerably strong cooperativity reveals that the polynucleosome state, condensed or not, is sensitive to small changes in he free histone H1 concentration around the value of 1/K. The association rate constant was of the order of 107 M−1·s−1 and had a small salt concentration dependence, indicating a diffusion‐controlled association process.
On the role of water‐soluble polypeptides (17, 23 kDa), calcium and chloride in photosynthetic oxygen evolution
Authors: Ghanotakis Demetrios F. , Babcock Gerald T. , Yocum Charles F.
Published: July 2002

Contrary to the assertion by Preston and Critchley [(1985) FEBS Lett. 184, 318‐332] that there is no correlation between calcium and water‐soluble 23 and 17 kDa polypeptides in promoting oxygen evolution activity, it can be shown that both calcium and the polypeptides are required for activity under physiological conditions. In the absence of the two polypeptides, non‐physiological concentrations of both calcium and chloride must be present for activity; neither ion can, by itself, promote high rates of oxygen evolution.
Comparison of the predicted secondary structure of aphid transmission factor for transmissible and non‐transmissible cauliflower mosaic virus strains
Authors: Modjtahedi N. , Volovitch M. , Mazzolini L. , Yot P.
Published: July 2002

Cauliflower Mosaic Virus (CaMV) aphid transmissibility depends on the concomitant presence of an 18 kDa polypeptide and an intact gene II coding for this P18 protein. The molecular basis of this phenomenon can now be analyzed since the complete nucleotide sequence is known for two transmissible (S and D/H) and one non‐transmissible strain (CM 1841). In order to get more detail on this topic, we have determined the nucleotide sequence of gene II and flanking regions for an additional strain PV147. The DNAs of strains CM1841 and PV147 show considerable homology (more than with strains S and D/H) but these strains have opposite phenotypes. In consequence, strain PV147 allows us to specify further the putative point mutations responsible for the lack of aphid transmission observed with CM 1841. The results obtained show that substitutions possibly involved in this defective phenotype are only two, instead of five on the basis of preexisting data. More interestingly, analysis of the potential effect of such substitutions upon predicted secondary structures of the different P18 polypeptides led us to a new hypothesis. Strain CM1841 could be mutated in the expression of gene II, a gene intact in other respects.
Processing of precursor ribosomal RNA and the presence of a modified ribosome assembly scheme in Escherichia coli relaxed strain
Authors: Mackow E.R. , Chang F.N.
Published: July 2002

An electrophoretic system capable of separating 25 S, 23 S, 17.5 S and 16 S ribosomal RNA (rRNA) species was used to study the synthesis and fate of rRNA during amino acid starvation and resupplementation of E. coli relaxed strain KL99. This E. coli relA1 strain responded to an amino acid starvation by increasing the rate of synthesis of 25 S and 17.5 S precursor rRNA. When the limiting amino acid was resupplemented, a previously observed 40‐fold increase in the cellular guanosine 5'‐diphosphate, 3'‐diphosphate content [Mol. Gen. Genet. (1983) 192, 5‐9] appeared to cause a reduction in new rRNA synthesis. Following amino acid resupplementation, the precursor 25 S and 17.5 S rRNA accumulated during the amino acid starvation were conserved and processed to 23 S and 16 S rRNA species, respectively. This suggests that a modified ribosome assembly scheme involving stable precursor rRNA exists in relA 1 bacteria during periods of amino acid limitation and resupplementation.
The 25 kDa protein kinase inhibitor present in liver cell is absent in fast growing HTC cells and is induced in sodium butyrate treated cells
Authors: Delpech Marc , Lévy-Favatier Florence , Tichonicky Lydie , Kruh Jacques
Published: July 2002

We have recently characterized a cAMP independent protein kinase inhibitor in rat liver. This inhibitor is absent or inactive in fast growing HTC cells and is induced according to exponential kinetics by sodium butyrate, a compound which arrests cell growth at the G1 phase of the cell cycle. It is suggested that the inhibitor could be involved in cell growth regulation.
The antigenic structure and topography of bacteriorhodopsin in purple membranes as determined by interaction with monoclonal antibodies
Authors: Ovchinnikov Yu.A. , Abdulaev N.G. , Vasilov R.G. , Vturina I.Yu. , Kuryatov A.B. , Kiselev A.V.
Published: July 2002

The spatial organization and the antigenic structure of the bacteriorhodopsin molecule in the purple membrane were studied by immunochemical techniques. Five monoclonal antibodies directed against exposed parts of the protein molecule in the membrane were prepared and characterized. Antigenic determinants were localized in the bacteriorhodopsin polypeptide chain by analysis of the interaction between monoclonal antibodies and protein fragments. The structure of antigenic determinants was revealed by the interaction of monoclonal antibodies with (i) isolated bacteriorhodopsin fragments further modified by sequential Edman degradation and (ii) derivatives of bacteriorhodopsin obtained biosynthetically or by selective chemical modification. Five antigenic determinants were localized in the following parts of bacteriorhodopsin: < Glu'‐Met20 involving one of the 3 amino acid residues of the N‐terminal part; Gly33‐Met56 involving Asp36 and/or Asp38 and Phe42; Phe156‐Met163 involving Phe156; Glu194‐Leu207 involving Glu194; Pro200‐Leu207.
Salmonella typhimurium rpoB and rpoC genes cloned on λ phages
Authors: Tittawella Ivor P.B.
Published: July 2002

Salmonella typhimurium rpoB and rpoC genes, coding for the RNA polymerase subunits β and β', respectively, were isolated on λ phages. Like their E. coli counterparts the two genes are closely linked and probably share a common promoter. The distribution of the target sites for several restriction enzymes, however, shows considerable divergence from the E. coli pattern.
A molecular mechanism for the biphasic effect of exogenous arachidonate on platelets
Authors: Jamaluddin Moideen P. , Krishnan Lissy K.
Published: July 2002

A haemoprotein (M
r
40 000) made up of two apparently identical subunits, and having Soret maximum at 405 nm, but displaying it mostly at about 410 nm or often at 415 nm in crude extracts owing to different bound small molecules, found in platelets of several species, has been purified from calf platelets. The purified protein could bind the stable PGH2 analogue, U‐46619, without co‐operativity (h = 1.0 and half‐maximal saturation concentration, S
0.5 = 10 μM) and arachidonate with co‐operativity that increased with arachidonate concentration (h increasing from 2̃ to 4̃). S
0.5 of arachidonate was 1.5 μM. Arachidonate binding to the protein was accompanied by its oligomerization.
Periodic heat production by oscillating glycolysis in a cytoplasmic medium extracted from yeast
Authors: Plesser T. , Müller S.C. , Hess B. , Lamprecht I. , Schaarschmidt B.
Published: July 2002

The rate of heat production in a periodically glycolysing cell‐free cytoplasmic medium extracted from yeast Saccharomyces cerevisiae is measured with a batch calorimeter. The rate exhibits periodic variations of approx. 10% of the average heat production rate of about 54 per minute. From this rate and the enthalpy change fro glycolysis a glucose degradation rate of 0.43 is calculated. The value fits into the ‘oscillatory window’ determined by a glucose injection technique.
Possible steroid binding site common to adrenal cytochrome P‐450scc and prostatic steroid binding protein
Authors: Gotoh O. , Tagashira Y. , Morohashi K. , Fujii-Kuriyama Y.
Published: July 2002

By searching the entire PIR‐protein‐sequence data base, we have found that a dodecapeptide sequence in bovine adrenal cytochrome P‐450scc is closely related to that in rat prostatic steroid binding protein. The two proteins belong to unrelated protein families, but both have steroids as substrates or ligands. Thus, the dodecapeptides may be important for substrate/ligand recognition in the individual proteins.
Quinolinate inhibition of gluconeogenesis is dependent on cytosolic oxalacetate concentration
Authors: Gabbay Robert A.
Published: July 2002

In isolated rat hepatocytes, the phosphoenolpyruvate carboxykinase (PEPCK) inhibitor, quinolinate decreased gluconeogenesis from lactate more than from pyruvate (78 vs 44%). Quinolinate inhibition of PEPCK has been reported to be competitive with oxalacetate (OAA), and therefore higher cytosolic OAA concentrations could be expected to alleviate quinolinate inhibition of PEPCK and hence reduce its effect on gluconeogenesis. With pyruvate as a carbon source, the cytosolic concentration of OAA was higher than with lactate (40 vs 9.7 μM). The levels of OAA were manipulated metabolically by adding asparagine (which provides more cytosolic OAA through the urea cycle) or oleate (which increases malate efflux from the mitochondria). In each of the 8 conditions studied, quinolinate inhibition of gluconeogenesis was inversely related to the levels of OAA in the cytosol. Quinolinate inhibition of asparagine gluconeogenesis was not due to a non‐specific effect on urea synthesis.
Purification and characterization of endonucleases DraII and III from Deinococcus radiophilus
Authors: de Wit C.M. , Dekker B.M.M. , Neele A.C. , de Waard A.
Published: July 2002

Deinococcus radiophilus strain ATCC 27603 contains, apart from endonuclease DraI [1], two additional sequence‐specific endonucleases. These enzymes, designated DraII and DraIII, recognize nucleotide sequences with novel specificities, PuG↓GNCCPy and CACNN↓GTG, respectively.
Implication of proteases in the respiration dependent inactivation of the lactose permease of E. coli
Authors: Therisod Hélène , Ghazi Alexandre , Shechter Emanuel
Published: July 2002

The lactose permease of E. coli becomes irreversibly inactivated during lactose transport under conditions of high respiratory activity. This inactivation is characterized by a decrease in the steady state of lactose accumulation, a decrease in the influx rate of lactose, and a decrease in the transmembrane electrical potential. We report here that inhibitors of serine proteases (phenylmethylsulfonyl fluoride and N‐α‐P‐tosyl‐L‐lysine chloromethyl ketone) prevent this inactivation, thus implicating proteases in this process.
Papain digestion of the subunits of (Na,K)‐ATPase
Authors: Kamimura Kazuyasu , Morohoshi Michiaki , Kawamura Masaru
Published: July 2002

Membrane‐bound (Na,K)‐ATPases were exposed to limited papain digestion. We could not find the active (Na,K)‐ATPase lacking glycoprotein subunit for the enzymes from three different sources (outer medulla of dog kidney, electric organs of Narkejaponica and larvae of Artemia
salina. It seemed unlikely that the glycoprotein subunit was selectively removed from (Na,K)‐ATPase by papain digestion
Heparin binding to lipoprotein lipase and low density lipoproteins
Authors: Jackson Richard L. , Socorro Lilian , Fletcher Geralyn M. , Cardin Alan D.
Published: July 2002

Heparin binding
Lipoprotein lipase
LDL
Apolipoprotein
Lipolysis
Electron microscopic analysis of the transcription of the Bacillus subtilis riboflavin operon inserted into the hybrid plasmid pLP102
Authors: Osina N.K. , Kalambet Yu.A. , Alexandrov A.A.
Published: July 2002

We used electron microscopy and computer analysis to study the Bacillus subtilis riboflavin operon transcription. The size of the riboflavin operon has been shown to be 2.40 ± 0.15 MDa. Transcription maps of the riboflavin operon in vitro and in vivo have been obtained. In the riboflavin operon region four transcripts are sythesized in vivo having the following approximate boundary positions in the map of pLP102: 46–52, 46–72, 62–72 and 55–58 map units. The riboflavin operon is transcribed from three promoters, at 46, 58 and 72 map positions. A scheme of the riboflavin operon transcription in B. subtilis is suggested.
Separation of isoenzymes of citrate synthase and isocitrate dehydrogenase by fast protein liquid chromatography
Authors: Mitchell C.G. , O'Neil S. , Reeves H.C. , Weitzman P.D.J.
Published: July 2002

Fast protein liquid chromatography (FPLC) has been shown to be a rapid and effective method of separating isoenzymes of citrate synthase and isocitrate dehydrogenase in extracts of Pseudomonas aeruginosa and Acinetobacter calcoaceticus The advantages of FPLC over conventional methods of fractionation are discussed and it is suggested that this may be a valuable and more general technique for isoenzyme resolution.
Guinea pig copeptin
Authors: Chauvet M.T. , Chauvet J. , Acher R.
Published: July 2002

The vasopressin precursor is composed of 3 domains in line, namely vasopressin, MSEL‐neurophysin and a glycopeptide referred to as copeptin, which are separated during the processing. In guinea pig neurohypophysis, the precursor is partially processed so that a two‐domain fragment, MSEL‐neurophysin ‐ copeptin, can be found along with free MSEL‐neurophysin and copeptin. Guinea pig copeptin has been sequenced. It is a glycopeptide composed of 38 amino acid residues rather than the 39 found in other mammalian copeptins. Compared with other copeptins, that from guinea pig shows a few substitutions and the deletion of one acidic residue, probably in position 32. This deletion might be responsible for incomplete cleavage by the trypsin‐like processing enzyme.
Enhancement in anti‐Semliki Forest virus activity of ds RNA by a muramyl dipeptide
Authors: George C.X. , Jain R.K. , Gupta C.M. , Anand Nitya
Published: July 2002

Antiviral activity of an interferon‐inducing mycoviral ds RNA against Semliki Forest virus infection was considerably enhanced by N‐palmitoylmuramyl‐L‐alanyl‐D‐isoglutamine (PMDP), a new muramyl dipeptide. This enhancement in activity was not due to increased production of interferon, but resulted probably from a PMDP‐induced increase in nonspecific resistance to infection. These results indicate that a combined treatment with an interferon inducer and muramyl dipeptide may prove highly useful to control effectively viral infections.
Glucose reduces both Rb+ influx and efflux in pancreatic islet cells
Authors: Lindström Per , Norlund Lena , Sehlin Janove
Published: July 2002

Microdissected, β‐cell‐rich pancreatic islets from ob/ob mice were used in studies of 86Rb+ transport. D‐Glucose (20 mM) induced a biphasic reduction in 86R+ efflux. The reduction stabilized within 10 min at 34% of the efflux rate at zero glucose. The initial 86Rb+ uptake (5 min) was dose‐dependently reduced by ouabain with maximum inhibition at 1 mM. D‐Glucose (20 mM) did not affect the ouabain‐sensitive 86Rb+ influx but markedly reduced (48%) the ouabain‐resistant isotope influx. The results suggest that D‐glucose does not affect the Na+/K+ pump in pancreatic β‐cells and that the glucose‐sensitive K+‐transporting modalities (K+ channels) in the β‐cells can mediate both inward and outward K+ flux.
Limitation in glucose penetration from the liver into blood and other metabolic symptoms of ethanol withdrawal in rats
Authors: Kosenko Elen A. , Kaminsky Yury G.
Published: July 2002

Studies were undertaken to determine whether the distribution of glycolytic intermediates between the blood and liver in rats would be changed upon ethanol consumption and after its withdrawal. More drastic impairment of energy metabolism appeared to occur after ethanol withdrawal than upon chronic ethanol ingestion. The major metabolic manifestations of withdrawal were severe hypoglycemia, hyperlactatemia and dramatic hypopyruvatemia. The liver/blood gradient of glucose attained a value of 4.2 after ethanol withdrawal, suggesting that glucose penetration from the liver into circulation became limited. Besides, glycogen was accumulated in the liver of withdrawn animals despite the severe hypoglycemia.
Immunochemical study of the plasma low and high density lipoproteins in Tangier disease
Authors: Dumon M.F. , Visvikis S. , Manabe T. , Clerc M.
Published: July 2002

Major disturbances of the lipoproteins in Tangier serum have been investigated using electrophoretic and immunochemical techniques. Previously described anomalies concerning the striking deficiency in HDL and the very low levels of apo A‐I and apo A‐II in Tangier patients are illustrated and explained. Anomalies concerning the fast LDL of Tangier serum are attributed to different forms of apo B not previously described. These data are strengthened by the features of a 2‐dimensional electrophoresis method elaborated in the laboratory which allows apoproteins to separate in the second dimension. These apoproteins are obtained by the delipidation of the lipoproteins fractionated in a first polyacrylamide discontinuous gel. This method clearly shows the distribution of apoproteins in the first lipoprotein track and is in perfect accordance with the new concept of lipoprotein particles.
Characterization of histone and protamine variants in sperm of the bivalve mollusc Aulacomya ater
Authors: Olivares Carlos , Ruiz Simón , Cornudella Lluis
Published: July 2002

The sperm nucleus of Aulacomya
ater, family Mytilidae, order Mytiloida, contains three proteins (X, Aa5 and Aa6) which are specific of this cell. These proteins have been isolated by CM chromatography and preparative electrophoresis. Electrophoretic analysis, amino acid composition, M
r determination and tryptic digestion show that protein X corresponds to a histone‐like protein whereas Aa5 and Aa6 are protamine‐like proteins.
Demonstration of intermediates between deoxy and carbonmonoxy hemoglobins by anaerobic high‐performance liquid chromatography
Authors: Anbari Mazen , Asakura Toshio
Published: July 2002

Intermediary ferrous hemoglobins (Hb) partially liganded with carbon monoxide (CO) were separated using an anaerobic high‐performance liquid chromatography system equipped with a cation‐exchange column at room temperature. Separations were achieved by applying various mixtures of oxy‐ and CO‐Hb A to the column. The mobile phase contained 3 mM sodium dithionite which deoxygenated the oxy hemes but left the CO hemes intact, thereby producing hemoglobins bound with various numbers of CO molecules. Spectrophotometric analyses of the eluent showed that hemoglobins were eluted in the order of deoxy hemoglobin, Hb(CO), Hb(CO)2, Hb(CO)3 and Hb(CO)4.
Reduction in potency and reversal of left‐shifting activity of BW12C with the major and minor components of chicken hemoglobin
Authors: Wootton Raymond , Stammers David K. , White Ralph D.
Published: July 2002

The effects of the left‐shifting, anti‐sickling compound BW12C (5‐(2‐formyl‐3‐hydroxyphenoxy)pentanoic acid) on the oxygen saturation curve of whole chicken blood and the isolated major (AII) and minor (AI) components of chicken hemoglobin have been studied. The results support the postulated major binding mode for BW12C to human hemoglobin of bridging between the α‐chain terminal amino groups in the oxy conformation with an important hydrophobic component contributed mainly by Pro 77α residues. In chicken AH (Pro 77 α → Ser) BW12C still left‐shifts at high concentrations but its potency is greatly reduced (at least 10‐fold). In chicken AI (Pro 77 α → Ser and Val 1 α → Met) BW12C is a right‐shifter with a potency comparable to that of 2,3‐diphosphoglycerate suggesting that binding at the β‐chain termini in the deoxy conformation is now dominant with α‐chain binding no longer significant.
A novel mechanism of resistance to α‐difluoromethylornithine induced by cycloheximide
Authors: Medrano Estela E. , Burrone Oscar R. , Ferrer Marcela M. , Cafferata Eduardo G.A. , Algranati Israel D.
Published: July 2002

Treatment of the chemically transformed fibroblasts BP‐A31 and other cell lines with low concentrations of cycloheximide (CHM) for 72 h followed by the removal of the protein synthesis inhibitor leads to the proliferation of α‐difluoromethylornithine (DFMO)‐resistant phenotypes. These drug‐resistant cells contain almost no ornithine decarboxylase (ODC) activity and concomitantly very low levels of putrescine and spermidine. Southern blot analysis and measurements of ODC activity and intracellular polyamine levels showed that the described mechanism of inducing resistance to DFMO triggered by CHM does not involve ODC gene amplification, altered transport of the drug or reduced affinity of the enzyme for DFMO.
Enzymatic quantification of strand breaks of DNA induced by vacuum‐UV radiation
Authors: Ito Takashi , Taniguchi Taketoshi
Published: July 2002

HindIII‐digested plasmid DNA dried on an aluminum plate was irradiated by vacuum‐UV at 160 and 195 nm using a synchrotron irradiation system. A change induced in the DNA, presumably a single strand break, was quantified by the aid of the strand break‐derived stimulation of poly(ADP‐ribose) synthetase activity. The end group of strand breaks so induced was recognized by the enzyme as effectively as that by DNase I treatment, suggesting a nicking as the major lesion inflicted on the DNA. The fluence (UV) dependent stimulation of poly(ADP‐ribose) synthetase activity was much higher upon 160 nm irradiation than upon 195 nm irradiation.
Heterogeneity of protein kinase NII
Authors: Qi Shang-Le , Yukioka Munehiko , Morisawa Seiji , Inoue Akira
Published: July 2002

Protein kinase NII
Heterogeneity
Subunit polypeptide
2D Polyacrylamide gel electrophoresis
Alkaline phosphatase
Autophosphorylation
Bromoacetylalprenololmenthane binding to β‐receptors modulates the rate of hormone‐induced internalization but not desensitization in S49 cells
Authors: Box Rainer-Joachim , Staehelin Matthys
Published: July 2002

Bromoacetylalprenololmenthane was found to inhibit hormone‐induced β‐adrenergic receptor internalization in a dose‐dependent fashion in S49 lymphoma cells, besides its known ability to bind to β‐receptors irreversibly. This new found property of BAAM+ was taken advantage of in studying whether receptor internalization is a necessary step in the desensitization of adenylate cyclase. BAAM‐treated cells showed functional desensitization even when receptor internalization had been blocked substantially by 50–65% This finding suggests that receptor internalization is not directly involved in desensitization.
Epidermal growth factor as a new regulator of induction of tyrosine aminotransferase and tryptophan oxygenase by glucocorticoids
Authors: Kido Hiroshi , Fukusen Naomi , Katunuma Nobuhiko
Published: July 2002

Epidermal growth factor (EGF) dose‐dependently enhanced the induction of tyrosine aminotransferase and tryptophan oxygenase by glucocorticoids in primary cultures of adult rat hepatocytes without itself having any effect on these enzymes in the absence of glucocorticoids. The amplifications were observed even with dexamethasone at high concentrations (10−6 M−10−5 M) that had a maximal effect. EGF had no effect on induction of tyrosine aminotransferase by glucagon or Bt2cAMP. The effect of EGF was also observed in adrenal‐ectomized and submaxillar gland‐ectomized rats. These results suggest that EGF is an endogenous amplifier of the action of glucocorticoids.
Crystallization of the Ca2+‐ATPase of skeletal muscle sarcoplasmic reticulum Inhibition by myotoxin a
Authors: Maurer Andreas , Tu Anthony T. , Volpe Pompeo
Published: July 2002

Decavanadate produces extensive ordered arrays of Ca2+‐ATPase molecules on sarcoplasmic reticulum (SR) vesicle surfaces [(1984) J. Bioenerg. Biomembranes 16, 491–505] and the basic unit of these crystalline structures seems to be a dimer of Ca2+‐ATPase [(]983) J. Ultrastruct. Res. 24, 454–464; (1984) J. Mol. Biol. 174, 193–204]. Myotoxin a, isolated from the venom of the prairie rattlesnake Crotalus viridis viridis, is a muscle‐degenerating polypeptide and its primary site of interaction is the SR membrane, where it uncouples Ca2+‐translocation from Ca2+‐dependent ATP hydrolysis [(1986) Arch. Biochem. Biophys. 246, 90–97]. The effect of myotoxin a on decavanadate‐induced two‐dimensional Ca2+‐ATPase crystals of SR membranes has been investigated. The toxin inhibits the formation of two‐dimensional SR‐membrane crystals and disrupts previously formed crystals in a time‐ and concentration‐dependent manner, which parallels the uncoupling of ATP hydrolysis from Ca2+ translocation. Two‐dimensional crystalline arrays of the SR membrane have a typical diffraction pattern which, after myotoxin a treatment, displays a progressive loss of order. Decavanadate is an uncompetitive inhibitor of the Ca2+‐ATPase enzyme‐myotoxin a complex. The present results suggest that a Ca2+‐ATPase dimer is required for coupling Ca2+ translocation to Ca2+‐dependent ATP hydrolysis.
Groove selectivity in the interaction of 9‐aminoacridine‐4‐carboxamide antitumor agents with DNA
Authors: Chen K.-X. , Gresh N. , Pullman B.
Published: July 2002

Theoretical quantitative evaluation of the intercalative binding to DNA of the new antitumor drug 9‐amino‐acridine‐4‐carboxamide indicates that, in contradiction with a recently proposed model, the compound should show specificity for interaction with the major (and not minor) groove of GC sequences.
Chiral β and random fractional deuteration for the determination of protein sidechain conformation by NMR
Authors: LeMaster David M.
Published: July 2002

Stereospecific assignments of the aspartic acid and asparagine, β‐protons of the 108 residue protein E. coli thioredoxin have been obtained by the use of chiral deuteration. In addition protein samples have been prepared in which all carbon bound hydrogen positions are substituted to an extent of 75% with deuterium. These random fractionally deuterated samples significantly facilitate the measurement of coupling constants and intraresidue NOE intensities which combined with the stereospecific assignments have provided determination of the first sidechain dihedral angle ϰ1, for all four asparagine residues and eight of the ten assigned aspartic acid residues.
Differences between individuals in high‐Mr glycoproteins from human mammary epithelia
Authors: Patton Stuart , Huston Gail E.
Published: July 2002

SDS‐polyacrylamide gel electrophoretic analysis of high molecular mass glycoproteins from human milk fat globules revealed that the pattern of bands is unique for each milk donor. The number, position, width and intensity of bands varied between donors. A difference in the pattern of sisters could be discerned. There is evidence that these mucin‐like glycoproteins, which originate from the plasma membrane of the mammary epithelial cell, occur in other cells and tissues. They may function in the immunorecognition system because of their individual‐specific character and cell surface location.
Isolation and identification of a specific and reversible inhibitor of starfish development
Authors: Tsuchimori Noboru , Miyashiro Shigeyoshi , Shibai Hiroshiro , Ikegami Susumu
Published: July 2002

An inhibitor of development of the starfish Asterina pectinifera was purified to homogeneity from a culture of the bacterium Bacillus subtilis, and was identified as adenosine. Adenosine at 6 μg/ml was shown to halt embryonic development specifically at the 256‐cell stage when all the embryonic cells differentiate into epithelial cells. By returning treated embryos to normal seawater, they developed normally to the bipinnaria stage.
Conformational changes in diphtheria toxoids
Authors: Bigio Massimo , Rossi Roberta , Nucci Daniele , Antoni Guido , Rappuoli Rino , Ratti Giulio
Published: July 2002

Monoclonal antibodies (Mab) were raised against CRM197, a non‐toxic mutant of diphtheria toxin (DT). The ability of four Mabs to bind DT and the six functional mutants CRM197, CRM176, CRM228, CRM1001, CRM45 and CRM30 was assessed by immunoblotting and by a radioimmunoassay in which the protein antigen in solution competes with labeled CRM197 for the Mab binding site. The results show that the peptides recognized by Mab11.3, Mab53 and Mab23 are accessible in the mutant molecules in solution but not when they are part of the native DT structure, which could therefore be described for this purpose as ‘closed’ in contrast with an ‘open’ conformation of CRM197, CRM176 and CRM228. In particular, the behaviour of Mab53 indicates that the single amino acid substitutions in the A fragments of CRM197 and CRM176 also affect the conformation of their B fragments.
Antibodies to normal and Alzheimer human brain structures from non‐immunised mice of various ages
Authors: Simpson James , Milne Ian H. , Gardner John O. , Yates Celia M. , James Keith , Fink George
Published: July 2002

Supernatants from mouse spleen hybridoma lines established without previous immunisation were screened immunohistochemically against cryostat sections of human temporal cortex and found to stain a variety of brain structures, including Alzheimer plaques and tangles. The age of the mice had no effect on antibody production.
A 22 kDa ras‐related G‐protein is the substrate for an ADP‐ribosyltransferase from Clostridium botulinum
Authors: Quilliam Lawrence A. , Brown Joan Heller , Buss Janice E.
Published: July 2002

A ribosyltransferase from C. botulinum type D ADP‐ribosylated a protein of 22 kDa (p22) in human astrocytoma (1321N1) cells. ADP‐ribosylation of membrane‐bound p22 was potentiated by 2 mM MgCl2 or guanine nucleotides but was much reduced in the presence of 10 mM Mg2+ plus GTPγS. p22 was immunoprecipitated by a monoclonal antibody 142‐24E05 raised against a peptide sequence common to the ras gene family but not by other ras or G‐protein antibodies. p22 was also ADP‐ribosylated in Drosophila but was not detected in Diclyostelium. These data suggest that the 22 kDa botulinum toxin substrate is a GTP‐binding protein and a member of the ras protein family.
Phosphatidylinositol kinase activity of a plasma membrane‐associated calcium‐activated protein kinase from pea
Authors: Blowers D.P. , Trewavas A.J.
Published: July 2002

A purified protein kinase preparation from pea is shown to contain phosphatidylinositol kinase activity. The preparation, produced by membrane solubilisation and ATP‐agarose affinity chromatography, contains proteins of 18 kDa (ppl8, a calcium activated autophosphorylating protein‐serine kinase), 67 kDa and 48 kDa and exhibits the phosphorylation of an endogenous lipid when supplied with [γ‐32P]ATP. This product is tentatively identified as lysophosphatidylinositol phosphate. When supplied with [γ‐32P]ATP and exogenous phosphatidylinositol, the production of phosphatidylinositol phosphate is observed.
1H‐NMR study of plantacyanin from spinach
Authors: Babayan M.A. , Nersissian A.M. , Nalbandyan R.M.
Published: July 2002

High‐resolution 1H‐NMR studies of spinach plantacyanin in its oxidized, reduced and apo‐forms revealed that two histidines, one tryptophan and at least one methionine are very close to copper. These amino acids seem to be considered as possible ligands of copper in the protein. Spinach plantacyanin, as well as the cucumber protein, has the hydrophobic core around its copper.
Similarity of protein conformation at low pH and high temperature observed for B‐chains of two plant toxins: ricin and mistletoe lectin 1
Authors: Bushueva T.L. , Tonevitsky A.G.
Published: July 2002

A comparative study of subunits of two plant toxins, ricin (RC) and mistletoe lectin 1 (ML 1), has been undertaken. The study suggests that isolated B‐chains of these toxins undergo structural transitions at low pH (from 5 to 4) and high temperature (45°C), and as a result of the guanidine hydrochloride denaturing effect (to 3 M). Our results indicate that the protein conformation observed at low pH and high temperature are similar, though not identical. These conformations differ from the native one (pH 7, 25°C), the protein in these conformations has a low fluorescence tryptophan intensity, and tryptophans are more exposed to aqueous solutions. However, these conformations differ also from the state unfolded by guanidine hydrochloride. An assumption is made that the partially denatured protein structure, exhibited at low pH and high temperature, is a functionally essential intermediate state of the toxin B‐chain.
GTPγS activation of proto‐oncogene expression in transiently permeabilised Swiss 3T3 fibroblasts
Authors: Pennington Stephen R. , Hesketh T.Robin , Metcalfe James C.
Published: July 2002

A technique of transient permeabilisation has been used to show that the introduction of guanosine 5′‐O‐(3‐thiotriphosphate) (GTPγS), a non‐hydrolysable analogue of GTP, into intact Swiss 3T3 fibroblasts stimulates phosphoinositide hydrolysis, cyclic AMP accumulation and the activation of c‐fos and c‐myc proto‐oncogenes. Of a number of nucleotide triphosphates introduced into the cells, only GTP and its non‐hydrolysable analogues activated inositol phosphate release, suggesting that this response is mediated by guanine nucleotide regulatory (G) protein(s). The data demonstrate that transient permeabilisation provides a method of examining the involvement of G‐proteins in nuclear activation.
Ethanolamine base exchange enzymatic activities in spontaneous transformed glial cell lines Effect of dibutyryl cyclic AMP treatment
Authors: El-Achkar P. , Mandel P. , Mersel M.
Published: July 2002

Cultured astrocytes derived from neonatal rats (normal cells) displayed maximal ethanolamine base exchange enzymatic activity (EBEE) when cultures reached confluency and cells almost ceased to divide. At this stage, ethanolamine phosphotransferase (EPT) and choline base exchange enzyme (CBEE) activities reached a plateau. In spontaneously transformed glial cells, no differential activity variation either between EPT and CBEE, or between EPT and EBEE was observed. The EBEE activity was mainly localized in the microsomal fraction and was completely absent from plasma membranes. Dibutyryl cyclic AMP (db‐cAMP) treatment of the transformed cells reversed the pattern of these activities to that of normal cells. Moreover, treatment of the transformed cells with medium conditioned by normal astroblasts markedly increased EBEE activity. This study demonstrates that (i) variation of EBEE activity during cell growth differs in normal and in transformed cultured glial cells. (ii) EBEE activity may be modulated via both db‐cAMP and normal cell conditioned medium. Our findings suggest a possible implication of EBEE in the maturation and contact inhibition of cell growth.
Distinct dystrophin mRNA species are expressed in embryonic and adult mouse skeletal muscle
Authors: Dickson G. , Pizzey J.A. , Elsom V.E. , Love D. , Davies K.E. , Walsh F.S.
Published: July 2002

We have examined dystrophin mRNA in embryonic, newborn and adult mouse skeletal muscle. A discrete nerve‐independent increase in mRNA size was observed between embryonic and adult stages, indicating that a developmentally regulated mRNA isoform switch occurs in the expression of the Duchenne muscular dystrophy (DMD) gene in skeletal muscle. These distinct mRNAs are most likely generated via selection of alternative transcriptional start sites or RNA processing pathways. In addition, denervation of adult muscle was without effect on the expression pattern.
Expression of the SmB′ splicing protein in rodent cells capable of following an alternative RNA splicing pathway
Authors: Sharpe Neil G. , Williams David G. , Norton Pamela , Latchman David S.
Published: July 2002

The expression of the SmB and SmB′ spliceosome proteins in a variety of cell types and tissues has been investigated. Although SmB is found in all cells studied, the SmB′ protein is found only in a small number of rodent cell types. The presence of this protein is correlated with the ability to utilize an alternative pathway of RNA splicing which is not available in most cell types. This is the first demonstration of tissue specific expression of a protein component of the spliceosome and suggests a role for SmB′ in the regulation of some cases of alternative RNA splicing.
Binding and oxidation of mutant cytochromes c by cytochrome‐c oxidase
Authors: Michel B. , Mauk A.G. , Bosshard H.R.
Published: July 2002

Mutation of conserved Phe‐82 of yeast iso‐1 cytochrome c to Tyr, Gly, Ser, Leu, or Ile affects binding to and reaction with cytochrome‐c oxidase from beef heart. The observed changes of binding and kinetic constants reflect mutation‐induced rearrangements in the heme vicinity brought about by the replacement of Phe‐82. Such conformational rearrangements are also revealed by altered circular dichroism spectra of the oxidase‐bound mutant cytochromes c. Variations in K
m for cytochrome c oxidation do not parallel variations in K
d, the dissociation constant for binding of cytochrome c to the oxidase. This observation does not support an enzymatic mechanism in which the rate of cytochrome c oxidation is governed by product dissociation.
Interferon (IFN)‐like antiviral effect is induced by unspecific cross‐linking of cell surface receptors
Authors: Premecz György , Markovits Andrea , Bagi György , Farkas Tibor , Földes István
Published: July 2002

Treatment of human amniotic cells (UAC) with Cytodex 1 (DEAE‐dextran) results in the development of an antiviral state of the cells, as proven by studying (i) the cytopathic effect and (ii) [3H]uridine incorporation into the RNA of vesicular stomatitis virus (VSV) after VSV infection. The same treatment transiently triggers the breakdown of inositol phospholipids and activates the translocation of protein kinase C (PKC). On the basis of these data it can be suggested that cross‐linking of cell surface receptors by a solid carrier bearing covalently bound positive charges may result in IFN‐like effects.
Chemical characterization of ligand binding site fragments from turkey β‐adrenergic receptor
Authors: Eshdat Y. , Chapot M.-P. , Strosberg A.D.
Published: July 2002

Affinity‐labeled β‐adrenergic receptor from turkey erythrocyte membranes was specifically cleaved near cysteine residues after S‐cyanylation. Analysis of the labeled polypeptide fragments suggests that iodocyanopindolol diazirine reacted with an amino acid residue which is located in the non‐glycosylated region containing the sixth and seventh transmembrane domains of the receptor. However, the possibility cannot be excluded that a second residue, located between the third and fifth transmembrane domains, was also labeled. Since treatment with either hydroxylamine or triethylamine resulted in removal of the affinity label from the protein, the present study suggests that aspartic or glutamic acid residues are present in the adrenergic‐binding site which is located in the above‐mentioned domains. The procedure for specific chemical cleavage of the affinity‐labeled adrenergic receptor should also be useful for future structural and comparative studies of other adrenergic receptors.
One left‐handed strand in DNA‐oligonucleotide complexes?
Authors: Gago Federico , Richards W.G.
Published: July 2002

A single strand of oligonucleotide can bind to double helical DNA under certain conditions. This must involve some unwinding of the original double helix in a process leading to the formation of a three‐stranded region. The free energy for such an entropically unlikely reaction may come from a change in the degree of supercoiling of the original DNA. The conformation of the triple strand is investigated here using computer graphics and molecular mechanics calculations. It is suggested that on binding the oligonucleotide (strand 3) to two paired strands (1 and 2) in a supercoiled DNA molecule, strand 2 might adopt a left‐handed conformation whilst strand 1 and strand 3 pair in the normal Watson‐Crick B‐configuration.