bluuebunny/crossref_metadata_2025 huggingface dataset:
Involvement of lysine residues in the binding of ovine chorionic somatomammotropin to lactogenic and somatotropic receptors
Authors: Chêne N. , Martal J. , de la Llosa P.
Published: July 2002

The biological activities of several ovine chorionic somatomammotropin (oCS) derivatives obtained by chemical modification of the lysine residues were studied by radioreceptor assays using rabbit mammary homogenates (lactogenic activity, L.A.) and liver homogenates (somatotropic activity, S.A.). Even if the control treatment with BH−
4 markedly decreased the L.A., it was clear that methylation mainly affected the S.A. and that ethylation reduced both activities. Guanidination inactivated almost completely both activities and acetimidination at a very low degree (3 of 14 lysines) led to less than 50% of both activities. These results show the involvement of lysine residues in the interaction of oCS with lactogenic and somatotropic receptors.
Cell cycle‐related changes in the surface properties of amoebae of the cellular slime mould Dictyostelium discoideum
Authors: Sharpe Paul T. , Watts D.J.
Published: July 2002

Amoebae of the cellular slime mould Dictyostelium discoideum were harvested during exponential, axenic growth and were partitioned in a dextran‐poly(ethylene glycol) two‐phase system in a countercurrent distribution apparatus. Amoebae in G1‐, S‐ and G2‐phases of the cell cycle were located in different parts of the countercurrent distribution. Since partitioning separates cells with different surface properties, it is concluded that there are cell cycle‐related changes in the surface properties, and thus plasma membrane structure, of the amoebae.
Hybrid 5 S ribosomal RNA encoded by a multicopy plasmid is incorporated into ribosomes of Escherichia coli
Authors: Szeberényi József , Apirion David
Published: July 2002

The recombinant plasmid pJR3Δ contains a tandem pair of promoters from rrnA followed by a hybrid 5 S rRNA gene, derived from the two 5 S rRNA genes of the rrnD transcription unit, and a terminator. Escherichia coli cells transformed with this plasmid produce 2–3‐times more 5 S rRNA compared to untransformed cells. The growth of cells containing this plasmid is not affected significantly. Although the sequence and the secondary structure of the plasmid‐specific 5 S rRNA differ from those of its counterparts (e.g., from 5 S rRNA species encoded by chromosomal genes), it is processed properly and is incorporated into ribosomes.
The differential effects produced by cis‐ and trans‐DDP on DNA in calf thymus nucleosomes
Authors: Simpkins H. , Pearlman L.F.
Published: July 2002

Calf thymus nucleosomes containing H1 were treated with dichlorodiammineplatinum (DDP) at low binding ratios (r = 0.05–0.15). Change in the electrophoretic mobility of the extracted nucleosomal DNA was observed following treatment with cis‐DDP and little change with trans‐DDP. There was a decrease in the electrophoretic mobility of the nucleosomal DNA as well as obliteration of the nucleosomal repeat distance. The fluorescence intensity of terbium binding to the extracted DNA showed minimal change following drug treatment. However, the thermal melting behavior of the nucleosomal DNA was altered to a greater extent following cis‐DDP treatment at 280 rather than 260 nm and a destabilization of the DNA helix was observed. These data suggest that in the whole nucleosome, cis‐DDP produces greater structural effects on the packaged DNA than trans‐DDP, although similar amounts of drug are bound with both isomers.
Nucleotide substitutions in a yeast mitochondria cis‐acting mutant located in the last nitron of the apocytochrome b gene
Authors: Bonjardim C.A. , Nóbrega F.G.
Published: July 2002

The region of mitochondrial DNA corresponding to the intron mutant M6‐200 in Saccharomyces cerevisiae D273‐10B has been isolated, and the nucleotide sequence of a 519 by RsaI fragment has been determined. Three nucleotide substitutions were found at nucleotides + 2650 (G → T), + 2668 (G → A) and + 2798 (A → G), all within the genetically defined location in the gene. Particular significance can be attributed to the first two changes (+ 2650 and + 2668), that can be genetically isolated from the third substitution and, in addition, alter conserved sequence features detected in a study [(1982) Biochimie 64, 867–881] of fungal mitochondrial introns.
Phosphorylation of mylein basic protein by glycogen phosphorylase kinase
Authors: Kobayashi Tomoko , Nakaza Toshiko , Negami Akira , Nakamura Shun-ichi , Yamamura Hirohei
Published: July 2002

The ability of homogeneous glycogen phorphorylase kinase (Phk) from rabbit skeletal muscle to phosphorylate bovine brain myelin basic protein (MBP) was investigated. Phk could incorporate a maximum of 1.9 mol phosphate/mol MBP. The apparent K
m and V
max for Phk phosphorylation of MBP were 27 μM and 90 nmol/min per mg enzyme, respectively. Properties of MBP phosphorylation by Phk are similar to those of phosphorylase as a substrate. Only serine residues of MBP are phosphorylated by Phk. Phosphorylation sites of MBP by Phk are not identical to those by cAMP‐dependent protein kinases.
Phase behavior of isolated photoreceptor membrane lipids is modulated by bivalent cations
Authors: Mollevanger Leo C.P.J. , De Grip Willem J.
Published: July 2002

The phase behavior of isolated photoreceptor membrane lipids is further investigated by 31P‐NMR, in view of earlier discrepant results [(1979) Biochim. Biophys. Acta 558, 330–337; (1982) FEBS Lett. 124, 93–99]. We present evidence that the discrepancy is due to bivalent cations. When resuspended in aqueous media at neutral pH in the absence of bivalent cations, the isolated photoreceptor membrane lipids largely adopt the bilayer configuration. However, upon addition of such cations (Ca2+ Mg2+) or when resuspended in their presence, the formation of other phases (hexagonal HII, lipidic particles) results. The rate of this transition depends on cation concentration and temperature. The transition is not easily reversed by addition of EDTA. Implications with regard to photoreceptor membrane structure and function need further study.
Isolation of Fc receptor shed from pig lymphocytes by a temperature shift
Authors: Vojtíšková Jarmila , Franěk František
Published: July 2002

Lymphocytes obtained from pig blood by gradient centrifugation were subjected to a temperature shift (4 to 37°C). The proteins released from the plasma membrane were fractionated by affinity chromatography using immunoglobulin G immobilized on fine polyamide particles. The main component liberated from the adsorbent by diethylamine buffer (pH 11.5) exhibited an apparent M
r of 18000–20000 in SDS—polyacrylamide gel electrophoresis. This crude receptor preparation possessed a substantially higher affinity to immobilized immunoglobulin G than to immobilized Fab fragment and inhibited significantly the binding of labeled immunoglobulin G to pig lymphocytes.
Regulation of protein synthesis in lymphoblastoid cells during inhibition of cell proliferation by human inteferons
Authors: Clemens Michael J. , McNurlan Margaret A. , Moore Graham , Tilleray Vivienne J.
Published: July 2002

Treatment of human lymphoblastoid (Daudi) cells with interferons inhibits cell proliferation in culture within 24 h. The failure of cell growth has been shown to be associated with impaired processing and decreased stability of newly replicated DNA. Because there is a close relationship between DNA replication and protein synthesis we have measured protein synthesis in intact Daudi cells. Protein synthesis declined steadily between 24 and 96 h after interferon treatment to a value which is only 20–30% of the rate in control cells. The enzyme 2′,5′‐oligo(A) synthetase is induced but our data do not support a role for the 2′,5′‐oligo(A)‐activated ribonuclease in the control of translation in this system.
Identification of Mr variants of proclatin with monoclonal antibodies
Authors: Aston R. , Young K. , van den Berg H. , Ivanyi J.
Published: July 2002

Monoclonal antibodies (QB01 and 1200) prepared against human proclatin (hPRL) have helped define a variant form of the hormone. This variant is of apparently higher molecular mass (26kDa) than the predominant form of the hormone (24kDa) and its presence does not appear to be species‐restricted. The demonstration of the 26 kDa form of the hPRL in fresh pituitary tissue and amniotic fluid suggests it may retain some specific function.
Cooperative and salt‐resistant binding of LexA protein to non‐operator DNA
Authors: Schnarr Manfred , Daune Michel
Published: July 2002

The interaction of the lexA repressor of E. coli with poly[d(A‐T)] has been studied by circular dichroism. The binding induces an about 2‐fold increase of the circular dichroism intensity at 263 nm, pointing out a conformational change of the nucleic acid. The observed spectral changes are very similar to those observed for the binding of the lac repressor to poly[d(A‐T)] and natural DNA. At elevated ionic strength the binding isotherms do show a pronounced sigmoidal shape indicating a cooperative mode of binding.
Effect of adenosine on insulin activation of rat adipocyte pyruvate dehydrogenase
Authors: Wong Ellen H.-A. , Smith Judith A. , Jarett Leonard
Published: July 2002

Adenosine and its analogue N
6‐phenylisopropyladenosine stimulated pyruvate dehydrogenase activity of isolated rat adipocytes. Maximal stimulation was obtained with concentrations between 50 and 100 μM, with the effect decreasing at higher concentrations. The effects of insulin on this enzyme was modified by adenosine. The concentration of insulin (10 ) that produced almost half‐maximal stimulation, had little or no effect, when adenosine deaminase was present. Adenosine also enhanced the effect of suboptimal but not optimal concentrations of insulin. Thus, the mechanism of adenosine action on adipocyte pyruvate dehydrogenase could in some way be similar or related to that of insulin.
Conformational state of circulating human plasma fibronectin
Authors: Rocco Mattia , Aresu Ottavia , Zardi Luciano
Published: July 2002

Fibronectin
Conformational state
Phosphorylation of ribosomal protein S6 and a peptide analogue of S6 by a protease‐activated kinase isolated from rat liver
Authors: Gabrielli Brian , Wettenhall Richard E.H. , Kemp Bruce E. , Quinn Michael , Bizonova Lily
Published: July 2002

A trypsin‐activated protein kinase has been isolated from rat liver using a peptide analogue of ribosomal protein S6 as a substrate in kinase assays. The structure of the peptide, Arg‐Arg‐Leu‐Ser‐Ser‐Leu‐Arg‐Ala, was based on a region of S6 containing both an insulin‐ and cyclic AMP‐regulated phosphorylation site. The trypsin‐activated protein kinase phosphorylated a corresponding site in the peptide analogue and ribosomal protein S6 that was distinct from the preferred site for cyclic AMP‐dependent protein kinase. Ribosomal S6 contained at least one other major site for the trypsin‐activated protein kinase.
Measurement of the rotational behaviour of virus particles during adsorption to the host cell surface
Authors: Bayer M.E. , Morrison I. , Cherry R.
Published: July 2002

The rotational diffusion of bacteriophage ϵ15 was measured before and after virus adsorption to outermembrane vesicles of the host Salmonella anatum. The virus capsid was labeled with eosin isothiocyanate, and the decay of transient dichroism following dye excitation by pulses of plane‐polarized light was measured. From the data, the rotational diffusion constant of the unadsorbed virion and its hydrodynamic diameter were estimated and found to be consistent with electron microscopic measurements of the capsid dimensions. Addition of outer membrane vesicles of S. anatum to the virus suspension revealed the immobilization of the virus particles on the membrane surface.
Metabolite‐mediated catalyst conversion of PFK and PFP: can PFK really be converted to PFP?
Authors: Gancedo Juana M.
Published: July 2002

It has been suggested that in spinach leaves an enzyme able to catalyze the phosphorylation of fructose 6‐phosphate to fructose 1,6‐bisphosphate can exist in two different interconvertible forms which use ATP and pyrophosphate respectively as phosphoryl donors [FEBS Letters 169 (1984) 287‐292]. However, the data presented to support this suggestion could also be interpreted without assuming such an unusual type of interconversion. This reinterpretation considers that PFK and PFP are two distinct enzymes which are differentially activated by incubation with various effectors such as UDPG, pyrophosphate, ATP, fructose 6‐phosphate and fructose 2,6‐bisphosphate.
Purification and properties of a plasmid‐encoded 2,4‐dichlorophenol hydroxylase
Authors: Liu Ting , Chapman Peter J.
Published: July 2002

2,4‐Dichlorophenol hydroxylase
2,4‐Dichlorophenoxyacetate plasmid
2,4‐Dichlorophenoxyacetate degradation
Alcaligenes eutrophus
Pseudomonas putida
Circular DNAs in mitochondria of Vicia faba
Authors: Eisner G.I. , Negruk V.I. , Cherny D.I. , Alexandrov A.A. , Shemyakin M.F. , Butenko R.G.
Published: July 2002

Electron microscopic analysis of Vicia faba mitochondrial DNA revealed two different types of circular DNA molecules. The class of small DNA molecules consisted mainly of circles near 1.6 kb in size, although a number of molecules were 2–3‐times longer. Large molecules ranged from 27 to 120 kb, and the majority of large circular DNA was represented by the molecules ranging from 37 to 67kb.
Decrease by glucagon in peroxide generation by isolated hepatocytes
Authors: Siess E.A. , Wieland O.H.
Published: July 2002

Exposure of isolated rat liver cells to glucagon or dibutyryl cyclic AMP leads to a prompt decrease in the rate of cellular peroxide generation as evidenced by (i) a reduced rate of [14C]formate oxidation and (ii) a lowered steady‐state concentration of catalase Compound I.
Restriction endonucleases from Bifidobacterium bifidum
Authors: Khosaka Toshiyuki , Kiwaki Mayumi
Published: July 2002

Three restriction endonucleases, BbiI, BbiII and BbiIII, have been isolated from Bifidobacterium bifidum. The recognition and cleavage specificity of BbiII was determined to be 5'‐GR↓CGYC‐3', identical to that of AcyI isolated from a cyanobacterium Anabaena cylindrica. The other two enzymes, BbiI and BbiIII, were found to be isoschizomers of PstI and XhoI, respectively.
Methylation of the SV40 HpaII site does not affect late viral gene expression in microinjected tissue culture cells
Authors: Graessmann M. , Ziechmann C. , Graessmann A.
Published: July 2002

Intranuclear coinjection of the late SV40 KpnI/Bcll DNA fragment and the early promotor/enhancer HpaII/BglI DNA segment into permissive monkey and non‐permissive mouse cells allows late SV40 gene expression without T‐antigen synthesis and DNA replication. These conditions were chosen to analyse the effect of DNA methylation on V‐antigen synthesis detached from the process of DNA replication. We found that in vitro methylation of a single cytosine nucleotide proximal to the major late mRNA cap site by the HpaII methylase does not block capsid protein synthesis. This result is in contrast to reported data obtained in Xenopus laevis oocyte injection experiments [(1982) Proc. Natl. Acad. Sci. USA 79, 5142‐5146].
Impairment of exogenous sphingomyelin degradation in cultured fibroblasts from familial hypercholesterolemia
Authors: Mazière J.C. , Mazière C. , Mora L. , Polonovski J.
Published: July 2002

The degradation of exogenous sphingomyelin was investigated in cultured fibroblasts from normal subjects and subjects with familial hypercholesterolemia, either in whole medium or in lipoprotein‐deficient medium. When introduced in whole medium, sphingomyelin degradation was significantly decreased (about 1.5‐fold) in heterozygotes, and dramatically (about 4‐fold) in homozygotes from familial hypercholesterolemia. Sphingomyelinase activity, measured in vitro by conventional methods, was not altered in fibroblasts from familial hypercholesterolemia. The sphingomyelin uptake was notably lower in familial hypercholesterolemia than in controls. The decrease in exogenous sphingomyelin degradation was also found in lipoprotein‐deficient medium, suggesting that it is not related to the low density lipoprotein receptor impairment which exists in familial hypercholesterolemia. These results are discussed in relation to sphingomyelin and cholesterol metabolism, and possible abnormalities of the cell membrane in familial hypercholesterolemia are suggested.
Biosynthesis of plasma membrane proteins from embryo cells of sea urchins at early embryogenesis
Authors: Sova V.V. , Chuguev Yu.P.
Published: July 2002

Studies on the biosynthesis of membrane proteins from embryo cells of Strongylocentrotus intermedius and Scaphechinus mirabilis sea urchins have revealed specificity in the synthesis of plasma membrane proteins at different stages of early embryogenesis (zygote, middle blastula, gastrula).
Polypeptide elongation factor Tu: observations on the interaction with DNase I and the aggregation at pH 6
Authors: Leberman Reuben
Published: July 2002

No evidence for the interaction of EF‐Tu with DNase I could be found by measuring the activities of each of the two proteins in the presence of excess of the other. Gel filtration of a mixture of the two proteins also provided no evidence for interaction. Aggregation at pH 6, observed with various samples of EF‐Tu, is apparently due to the aggregation of material which is not functional in the GDP exchange assay. These results indicate that there is no structural/evolutionary relationship between EF‐Tu and eukaryotic actin.
The decarboxylation of 3‐mercaptopyruvate to 2‐mercaptoacetate
Authors: Mårtensson Johannes , Nilsson Lennart , Sörbo Bo
Published: July 2002

Rat brain mitochondria were found to convert 3‐mercaptopyruvate to 2‐mercaptoacetate in the presence of NAD+ coenzyme A and thiamin pyrophosphate. The overall reaction probably consists of an oxidative decarboxylation of 3‐mercaptopyruvate with 2‐mercaptoacetyl CoA as a product which is then hydrolyzed to 2‐mercaptoacetate by acyl CoA hydrolase
Rapid reconstitution of a transmembrane protein into supported planar lipid membranes
Authors: Nakanishi Mamoru
Published: July 2002

A procedure for reconstituting a transmembrane protein by the freeze‐thaw method into supported planar lipid layers has been developed. A solution containing human glycophorin A was introduced between an alkylated cover glass with lipid layers from soybean phospholipids and a bare glass slide, and was then put in a glass dish which was frozen outside by liquid nitrogen. The lipid layer membranes prepared in this manner have been examined by the binding of both macrophages and wheat germ agglutinin agarose. Macrophages bound more efficiently to the membranes bearing glycophorin A and spread more rapidly than those of the control membranes.
Photoaffinity labelling of the nucleoside transporter of cultured mouse lymphoma cells
Authors: Almeida Anthony F. , Jarvis Simon M. , Young James D. , Paterson Alan R.P.
Published: July 2002

Nitrobenzylthioniosine (NBMPR), a potent and specific inhibitor of nucleoside transport, is bound reversibly by high affinity sites on nucleoside transporter proteins of erythrocyte membranes and, upon photoactivation, NBMPR molecules become covalently bonded to the sites. This study showed that [3H]NBMPR molecules reversibly bound to intact S49 and L5178Y mouse lymphoma cells became covalently bound upon exposure to UV light. Electrophoretic analysis of plasma membrane fractions from the labelled cells showed that 3H was present in polypeptides which migrated as a major band with an apparent M
r of 45000–65000.
Glycine and asparagme tRNA sequences from the archaebacteriuin, Methanobacterium thermoautotrophicum
Authors: Gu Xiang-Rong , Nicoghosian K. , Cedergren R.J.
Published: July 2002

Two tRNA sequences from Methanobacterium thermoautotrophium are reported. Both tRNAGly
GCC and tRNANUU
Asn, the first tRNA sequences from methanogens, were determined by partial hydrolyses (both chemical and enzymatic) and analyzed by gel electrophoresis. The two tRNAs contain the unusual T‐loop modifications, Cm and m1I, which are present in other archaebacterial tRNAs. Finally the presence of an unknown modification in the D‐loop has been inferred by a large jump in the sequence ladder. These tRNAs are approximately equidistant from eubacterial or eukaryotic tRNAs.
Fluctuations in phosphoribosyl pyrophosphate levels in monolayer tumor cell lines
Authors: Peters G.J. , Laurensse E. , Leyva A. , Pinedo H.M.
Published: July 2002

The concentration of PRPP (phosphoribosyl pyrophosphate) measured in tumor cells grown in monolayer showed a large variation with the various harvesting methods examined, including trypsinization. This variation could be reduced by a 1‐h incubation of trypsinized cells as a suspension in Dulbecco's medium. After this preincubation these cell suspensions were suitable for the study of modulation of PRPP. One μM methotrexate caused a 2–3‐fold increase and 1 mM N‐phosphonoacetyl‐L‐aspartate a slight increase, but inosine and deoxyinosine drastically reduced PRPP concentrations. 5‐Fluorouracil had no effect. This study demonstrates that metabolic parameters such as PRPP concentrations can be studied conveniently in suspensions of cells which are commonly cultivated as monolayers.
Enhancement of growth factor‐induced DNA synthesis by colon tumor‐promoting bile acids in Swiss 3T3 cells
Authors: Takeyama Yoshifumi , Kaibuchi Kozo , Ohyanagi Harumasa , Saitoh Yoichi , Takai Yoshimi
Published: July 2002

In Swiss 3T3 cells, colon tumor‐promoting deoxycholate (DOC) enhanced DNA synthesis which was induced by fibroblast growth factor (FGF) in the presence of insulin. This effect was observed only when DOC was added within 10 h after the addition of FGF. DOC by itself did not induce DNA synthesis irrespective of the presence or absence of insulin. Similar results were obtained with other colon tumor‐promoting bile acids such as cholate, chenodeoxycholate and taurocholate. In contrast to these bile acids, 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) induced DNA synthesis fully without FGF in the presence of insulin. DOC did not affect TPA‐induced DNA synthesis. Prolonged treatment of the cells with phorbol‐12, 13‐dibutyrate caused the down‐regulation of the phorbol ester receptor and rendered the cells unresponsive to TPA. In these cells, FGF still induced DNA synthesis in the presence of insulin, but the maximal level was reduced to about one third of that in the control cells. DOC did not enhance this DNA synthesis any more. DOC did not alter the binding of FGF to the cells. These results indicate that colon tumor‐promoting bile acids enhance the mitogenic action of FGF and thereby stimulate DNA synthesis, although the phorbol ester substitutes for the mitogenic action of FGF.
Acylation of adenovirus type 12 early region Ib 18‐kDa protein
Authors: Grand Roger J.A. , Roberts Carl , Gallimore Phillip H.
Published: July 2002

The 18‐kDa E1b protein in Ad 12‐transformed rat cells and in Ad 12‐infected human cells binds lipid strongly. The lipid is not removed by boiling in the presence of SDS or by extraction with methanol/chloroform. It is, however, dissociated from the protein by treatment with methanolic KOH suggesting that attachment is through an ester linkage. The acylated 18‐kDa protein is detected only in the membrane fraction. Labelling cell surface proteins on Ad 12‐transformed cells with [125I]iodosulphanilic acid shows that some of the Ad 12 18‐kDa E1b protein is present on the outside of the cell. It is concluded that this protein is responsible for cell surface T‐antigen activity.
A fluorimetry study of N‐(1‐pyrenyl)iodoacetamide‐labelled bovine brain S‐100a protein
Authors: Mani Rajam S. , Kay Cyril M.
Published: July 2002

S‐100 a protein has been modified with the thiol specific fluorescent label N‐(l‐pyrenyl) iodoacetamide. When the protein was reacted with the fluorophore in the presence of EDTA, only one sulfhydryl group was labelled. The labelled protein when excited at 344 nm had an emission maximum at 386 nm and a shoulder at 403 nm. Addition of calcium resulted in a quenching of the fluorescence intensity at 386 nm whereas Zn2+ addition caused an enhancement. Titration of labelled protein with CaCl2 or ZnSO4 yielded dissociation constants (K
D values) of 3 × 10−5 M and 8 × 10−6 M for Ca2+ and Zn2+, respectively. In the presence of 90 mM KCl the protein has a lower affinity towards calcium (K
D, 6 × 10−5 M). Acrylamide quenching studies revealed the probe to be more accessible to acrylamide in the plus calcium state. Reaction kinetics with DTNB in 0.1 M Tris buffer at pH 7.5 also suggested that the single reactive sulfhydryl group was more exposed to the solvent in the presence of Ca2+. Thus, the observed quenching of calcium addition may be the result of the probe moving to a relatively more polar environment. This would imply that the probe moves to a more nonpolar region in the presence of Zn2+. These results are in accord with our earlier near UV‐CD studies where the metal ions, calcium and zinc were observed to induce different conformational changes in S‐100a protein.
1H‐NMR study of the interaction of aminopyrine with purified rat liver microsomal cytochrome P‐450
Authors: Woldman Ya.Yu. , Weiner L.M. , Gulyaeva L.F. , Lyakhovich V.V.
Published: July 2002

Longitudinal relaxation (T
1) measurements for all lines (N(CH3)2, N(CH3), (C(CH3), phenyl) in the aminopyrine 1H‐NMR spectrum were used to study the interaction of aminopyrine with purified microsomal cytochrome P‐450 from livers of phenobarbital‐treated rats. The paramagnetic contribution to the observed t
1
−1 values was determined from its dependence on aminopyrine concentration. The Solomon‐Bloembergen equation was used to calculate between Fe3+ and aminopyrine distances in the enzyme‐substrate complex. For all protons these distances are about 8 Å.
Effect of dexamethasone on polypeptides synthesised in polymorphonuclear leucocytes
Authors: Blowers L.E. , Jayson M.I.V. , Jasani M.K.
Published: July 2002

The effect of a glucocorticoid on protein synthesis in human polymorphonuclear leucocytes (PMNLs) was investigated by two‐dimensional gel electrophoresis. In the peripheral blood PMNLs of healthy laboratory personnel, the rate of incorporation of L35S]methionine into a least nine polypeptides was consistently influenced by dexamethasone in a dose‐dependent manner, being increased in the case of seven polypeptides and decreased in the remainder.
An improved electrofusion technique for production of mouse hybridoma cells
Authors: Vienken J. , Zimmermann U.
Published: July 2002

An experimental procedure is described for the reproducible production of hybridoma cells using the electrofusion technique. High yields can be obtained when fusion is performed in isotonic inositol solutions containing Ca2+ and Mg2+ in a ratio of 1:5 in the millimolar range. The hybridoma cells are transferred 10 min after the field pulse application into a balanced salt solution for 30 min at 37°C.
Dissociation of actomyosin complex by monovalent fragments of polyclonal antibodies to myosin
Authors: Mazander K.D. , Gröschel-Stewart U.
Published: July 2002

The monovalent fragments of antibodies specific for skeletal muscle myosin inhibit myosin ATPase activity and dissociate the actomyosin complex, as shown by analytical ultracentrifugation and viscosity measurements.
Biochemical evidence that acetylcholine release from cholinergic nerve terminals is mostly vesicular
Authors: Michaelson Daniel M. , Burstein M.
Published: July 2002

The nature of the intraterminal compartments from which acetylcholine (ACh) is released following presynaptic stimulation was investigated. This was pursued by examining the effects of the anticholinergic drug 2‐(4‐phenylpiperidino)cyclohexanol (AH5183) on the release of newly synthesized [3H]ACh and of endogenous ACh from purified cholinergic nerve terminals (synaptosomes) which were isolated from the electric organs of Torpedo. Preincubation of the synaptosomes, with AH5183 (1–10 μM), does not affect either the intraterminal synthesis of [3H]ACh or the uptake of its precursors, but results in a marked inhibition (85%) of the release of the newly synthesized [3H]ACh. However, when AH5183 is added following the accumulation of [3H]ACh in the nerve terminals, it does not affect [3H]ACh release. AH5183 also has no effect on the release of preformed endogenous ACh. These findings, together with the previous in vitro demonstrations that AH5183 is a potent inhibitor of ACh uptake into isolated cholinergic vesicles, suggest that most of the synaptosomal ACh is secreted by a vesicular mechanism.
Transient deprotonation of bacterial halorhodopsin by photoexcited base
Authors: Gutman M. , Nachliel E.
Published: July 2002

The excited singlet state of 6‐methoxyquinoline is basic enough to abstract a proton from water and generate OH−. Pulse excitation of such a solution undergoes a massive transient alkalinization. This procedure was employed to monitor the deprotonation of the Schiff base of halorhodopsin. Both the deprotonation and reprotonation of the chromophore are diffusion controlled reactions.
Application of O‐(4‐diazo‐3‐[125I]iodobenzoyl)sucrose for the detection of the catabolic sites of low density lipoprotein
Authors: Van't Hooft F.M. , Van Tol A.
Published: July 2002

The sites of degradation of human low density lipoprotein (LDL), are analyzed using the novel labelling compound O‐(4‐diazo‐3‐[125I]iodobenzoyl)sucrose (D125IBS). The decay from rat serum of D125IBS‐labelled LDL is identical to the serum decay of conventionally iodinated (ICI method) LDL. The radioactivity derived from D125IBS‐labelled LDL accumulates predominantly in the liver after intravenous injection and the hepatic radioactivity remains associated with the lysosomal compartment for an extended period of time, when compared to the radioactivity derived from conventionally iodinated LDL. It is concluded that the D125IBS labelling procedure is an interesting new tool to study the sites of catabolism of serum lipoproteins.
Purification of protein phosphatase from hen oviduct
Authors: Kanayama Keiko , Wada Kenji , Negami Akira , Yamamura Hirohei , Tanabe Tadashi
Published: July 2002

Two protein phosphatases of 103 and 29 kDa as determined by gel filtration, were purified from hen oviducts. The 103 ‐kDa phosphatase was purified 7300‐fold to near homogeneity and dissociated into two polypeptides in the presence of SDS. Molecular masses of these polypeptides were estimated to be 60 and 38 kDa by SDS‐polyacrylamide slab gel electrophoresis using the buffer system of Laemmli, but 68 and 35 kDa using the buffer system of Weber and Osborn. The stoichiometry of these polypeptides was approx 1:1 according to the densitometric analysis of gels at 550 nm. The 29 ‐kDa phosphatase was purified 2900‐fold. Both phosphatases dephosphorylated the α‐subunit of phosphorylase kinase more rapidly than the β‐subunit.
Effect of dinucleotides on wheat germ translation system
Authors: Chroboczek Jadwiga , Jacrot Bernard
Published: July 2002

The effect of ribodinucleoside monophosphates on total protein synthesis was studied in a wheat germ cellfree system, using brome mosaic virus (BMV) RNA as a messenger. Dinucleotides inhibit total protein synthesis to different extents. Of those tested the most inhibitory is CpA. The inhibitory effect of dinucleotides is due to their adverse effect on initiation and not on elongation of polypeptide synthesis. It seems that the dinucleotides complementary to the initiation codon are able to compete with the initiator tRNA during initiation of protein synthesis. The comparison of the effect exerted by different dinucleotides suggests that under conditions of the in vitro protein synthesis RNA 4 is an mRNA molecule with the initiation codon and its immediate neighbourhood being exposed.
Monoclonal antibodies to cytochrome P‐450 immunopurify a 45‐kDa protein from a human lymphoblastoid cell line
Authors: Friedman Fred K. , Pastewka Jullia V. , Robinson Richard C. , Park Sang Shin , Marietta Michael A. , Gelboin Harry V.
Published: July 2002

Monoclonal antibodies (MAbs) to rat liver cytochromes P‐450 have previously been used for successful immunopurification of cytochromes P‐450 from animal tissues. We now report application of this MAb‐based immunopurification technique to the human lymphoblastoid AHH‐1 cell line. Immunopurification carried out with 3 different MAbs each yielded a 45‐kDa polypeptide. The purified protein contains an MAb‐specific epitope present on cytochromes P‐450, and may therefore be a human cytochrome P‐450.
Calcium‐activated, phospholipid‐dependent protein kinase activity and protein phosphorylation in HL60 cells induced to differentiate by retinoic acid
Authors: Durham John P. , Emler Carol A. , Butcher Fred R. , Fontana Joseph A.
Published: July 2002

Treatment of human promyelocytic (HL60) cells with retinoic acid for at least 48 h causes differentiation to more mature myeloid forms. Prior to commitment of cells to the myeloid pathway there is a marked increase in cytosolic calcium‐activated, phospholipid‐dependent protein kinase activity. This increase does not result from an intracellular redistribution of the enzyme. Concomitant with the increased enzyme activity there is enhanced phospholipid‐dependent phosphorylation of proteins of 29, 49, 52, 58, 68, 69, 120, 170, 200 and 245 kDa.
Reconstitution of the epidermal growth factor receptor in artificial lipid bilayers
Authors: Panayotou George N. , Magee Anthony I. , Geisow Michael J.
Published: July 2002

Epidermal growth factor receptor, isolated in the presence of the non‐ionic detergent octylglucoside, was reconstituted into liposomes by detergent dialysis. The receptor was shown to be incorporated in the lipid bilayer with the EGF binding domain oriented to the outside of the liposomes and to retain its ability to bind EGF and an anti‐receptor antibody in a specific manner.
The role of inorganic pyrophosphatase regulatory centres in subunit interactions
Authors: Vorobyeva Natalia N. , Nazarova Tatiana I. , Avaeva Svetlana M.
Published: July 2002

A baker's yeast inorganic pyrophosphatase derivative has been obtained in which one carboxyl group of each regulatory centre is converted to hydroxamate. This enzyme retains the capacity to hydrolyze the substrate while remaining a dimer. However, introduction of ligands to the active centre of one subunit of such enzyme does not affect the conformation of the other as is the case with native pyrophosphatase, i.e., the regulatory centre‐modified enzyme behaves as a monomer. Thus, selective modification of the regulatory centres results in the disappearance of subunit interactions.
Equilibrium between monomers and oligomers of soluble Ca2+‐ATPase during the functional cycle
Authors: Andersen Jens P. , Vilsen Bente
Published: July 2002

High performance liquid chromatography
Detergent
Ca2+ transport
Vanadate
Sarcoplasmic reticulum
Protein‐protein interaction
A monoclonal antibody reacting specifically with ganglioside GD1b in human brain
Authors: Fredman P. , Jeansson S. , Lycke E. , Svennerholm L.
Published: July 2002

Monoclonal antibody
Brain ganglioside
Ganglioside GD1b‐specificity
Oligonucleotide‐directed mutagenesis of the Rhizobium japonicum nifH promoter
Authors: Kaluza Klaus , Alvarez-Morales Ariel , Hennecke Hauke
Published: July 2002

A deoxyguanosine (G) to deoxythymidine (T) transversion was introduced, by site‐specific mutagenesis, at position −25 of the nif consensus promoter sequence. It resulted in a 92% decrease of promoter activity when tested in an enterobacterial NtrA+NifA+ system that was known to activate Rhizobium japonicum nitrogenase promoters. Two other mutations, in regions that were previously speculated to be of potential importance for nifH expression [(1984) Mol. Gen. Genet. 196, 35‐42; (1984) J. Mol. Appl. Genet. 2, 395‐405], were without severe effect.
The primary structure of two polypeptide chains from preparations of homeostatic thymus hormone (HTHα and HTHβ)
Authors: Reichhart Robert , Jörnvall Hans , Carlquist Mats , Zeppezauer Michael
Published: July 2002

The primary structures of the 2 polypeptide chains (HTHα and HTHβ) of the homeostatic thymus hormone (HTH) were determined. The entire structures were found to be identical to those of histones H2A and H2B, respectively, without evidence for sub‐types, proteolytic processings, or other peptide fragments. The results show that suggestions for new extranuclear and hormone‐like histone functions apply to HTH preparations with intact protein chains of the H2 histones
2',3'‐Dialdehyde of GTP blocks regulatory functions of adenylate cyclase Ns protein
Authors: Skurat Alexander V. , Yurkova Maria S. , Khropov Yuri V. , Bulargina Tamara V. , Severin Eugene S.
Published: July 2002

Preincubation of bovine caudate nucleus membranes with the 2',3'‐dialdehyde of GTP (oGTP) reduces adenylate cyclase activation by guanylyl imidodiphosphate (GppNHp) in a time‐dependent fashion. A slower rate of inhibition is observed if membranes are treated with both GTP and oGTP. The efficacy of oGTP action is enhanced by raising the Mg2+ concentration. Reduction of adenylate cyclase sensitivity to GppNHp is followed by an irreversible decrease of enzyme stimulation by forskolin. Addition of a Lubrol soluble preparation from guinea pig lung membranes to oGTP‐treated caudate nucleus membranes causes restoration of the adenylate cyclase sensitivity to GppNHp. These data suggest that oGTP blocks the GTP‐binding site of the adenylate cyclase system localized on the Ns protein. Such modification leads to the elimination of the Ns‐mediated regulation of the enzyme.
Alterations in mitochondrial aconitase activity and respiration, and in concentration of citrate in some organs of mice with experimental or genetic diabetes
Authors: Boquist L. , Ericsson I. , Lorentzon R. , Nelson L.
Published: July 2002

Aconitase
Alloxan
Citrate
Diabetes
Mitochondria
Respiration
Membrane crystals of Ca2+‐ATPase in sarcoplasmic reticulum of developing muscle
Authors: Dux László
Published: July 2002

Sarcoplasmic reticulum development
Skeletal muscle
Ca2+‐transport ATPase
Evidence that progesterone binding uteroglobin is similar to myosin alkali light chain
Authors: Baker Michael E.
Published: July 2002

Using a computer program designed to detect evolutionary relationships between proteins, I find that exon 2 of rabbit uteroglobin, a progesterone binder, and part of myosin alkali light chain have a comparison score that is 7.2 standard deviations higher than that obtained with a comparison of randomized sequences of these proteins. The probability (p) of getting this score by chance is less than 10−12. This theoretical finding that these sequences are similar has led to the experimental finding that copper, calcium and the tranquilizer trifluoperazine, a calmodulin binding ligand, affect progesterone binding to uteroglobin.
Modification of mammalian fatty acid synthetase activity by NADP
Authors: Smith Stuart , Linn Tracy , Stern Alan
Published: July 2002

Experiments are described which show that the mammalian fatty acid synthetase, in the presence of NADP, synthesizes stoichiometric amounts of enzyme‐bound acetoacetyl moieties. The acetoacetyl moieties can neither undergo the normal transfer reaction to a CoA acceptor, nor participate in the normal reaction sequence once NADPH is made available. Our results indicate that, since it is the product of the condensation reaction which accumulates on the inhibited enzyme, the previously held view that NADP inhibits the condensation step in fatty acid synthesis is probably incorrect.
An endonuclease closely associated with DNA‐dependent RNA polymerase II
Authors: Szopa Jan , Rzepecki Ryszard , Wojtkiewicz Beata , Szmidzinski Ryszard
Published: July 2002

An endonuclease tightly bound to RNA polymerase II has been purified. The enzyme consists of two subunits, and is essential for the polymerase activity.
Regulation of the production of granulocyte‐macrophage colony‐stimulating factor by macrophage‐like tumour cell lines
Authors: Hume David A. , Summers Kim M. , Cohen Donna R. , Allan William
Published: July 2002

Macrophage tumour cell lines (PU5‐1.8, P388D1) produced detectable granulocyte macrophage colonystimulating (CSF‐2) activity measured using a factor‐dependent cell line FDC‐P1. The production ofCSF‐2 was enhanced by endotoxin and inhibited by serum, and correlated inversely with [3H]TdR incorporation. mRNA isolated from PU5‐1.8 or P388D1 cells initiated CSF‐2 production when injected into Xenopus laevis oocytes. The specific activity in this assay was unaltered in mRNA isolated from endotoxin‐treated cells. The results suggest that endotoxin acts at a post‐transcriptional level.
Pre‐replicative changes of the rat sinusoidal plasma membrane glycoproteins during hepatic regeneration
Authors: Enrich Carlos , Gahmberg Carl G.
Published: July 2002

Cell‐surface glycoproteins of rat liver sinusoidal plasma membranes from control and regenerating livers were studied. The glycoproteins were labeled using specific methods for sialic acid (NAIO4/NaB3H4) and galactosyl/N‐acetyl galctosaminyl residues (galactose oxidase/NaB3H4 and neuraminidase‐galactose oxidase (NaB3H4) and the solubilized proteins were analyzed by gel electrophoresis. The patterns obtained with regenerating livers were quantitatively different from controls. This shows that cell surface glycoproteins change during liver regeneration.
β2‐Inhibin contains the active core of human seminal plasma β‐inhibin: synthesis and bioactivity
Authors: Arbatti N.J. , Seidah N.G. , Rochemont J. , Escher E. , Sheth A.R. , Chrétien M.
Published: July 2002

The complete synthesis of the C‐terminal 28 residues segment 67–94 of human seminal plasma jS‐Inhibin, called β2‐Inhibin, is reported. The Inhibin‐like activity of the native 94 amino acids β‐Inhibin is compared to that of the synthetic replica of β2‐Inhibin. In all assays used both peptides effectively suppress the FSH release induced by LHRH but have little effect on the LH release. In the mouse both peptides are equipotent on a mole basis. In the rat the synthetic β2‐Inhibin is 3–10 times more potent than β‐Inhibin. Both peptides are active in rat anterior pituitary primary culture assays where maximum suppression of FSH release induced by LHRH occurs around 300 of β2‐Inhibin. In contrast, maximum suppression of FSH release in the mouse pituitary assay occurs at 10–15 of either Inhibin.
Protein phosphorylation in the photosynthetic bacterium Rhodospirillum rubrum
Authors: Holuigue Loreto , Lucero Héctor A. , Vallejos Rubén H.
Published: July 2002

Endogenous protein phosphorylation in cellular fractions from Rhodospirillum rubrum was manifested after exposure to [γ‐32P]ATP. At least six phosphorylated protein bands of 90, 86, 64, 31, 13 and 11 kDa were found in the cell‐free extract. Treatment of the 64‐kDa band with V8 protease yielded smaller radioactive bands. Phosphoserine, phosphothreonine and phosphotyrosine were detected after acid hydrolysis of the phosphorylated fractions. Protein phosphorylation in all the fractions was insensitive to cAMP, did not recognize exogenous protein substrates and was rapidly reverted upon elimination of the excess of [γ‐32P]ATP. The chlorophyll‐anthena apoprotein from R. rubrum chromatophores overlapped the 13‐kDa phosphorylated band during gel filtration by high‐pressure liquid chromatography suggesting that it is one of the substrates of the protein kinase(s) of R. rubrum.
Excitation energy transfer in Rhodopseudomonas sphaeroides chromatophore membranes fused with liposomes
Authors: Pennoyer Jeffrey D. , Kramer Herman J.M. , van Grondelle Rienk , Westerhuis Willem H.J. , Amesz Jan , Niederman Robert A.
Published: July 2002

Bacterial photosynthesis
Bacteriochlorophyll‐protein complex
Fluorescence spectroscopy
Light‐harvesting complex
Liposome fusion
Photosynthetic membrane
(Rhodopseudomonas sphaeroides)
Structural studies of calmodulin and related calcium‐binding proteins by hydrophobic labeling
Authors: Buerkler Jacqueline , Krebs Joachim
Published: July 2002

The highly hydrophobic, photoreactive probe 3‐(trifluoromethyl)‐3‐(m‐[125I]iodophenyl)diazirine ([125I]TID) labels calmodulin in a Ca2+‐dependent way [(1984) Biochemistry 23, 400–403]. Similar results are obtained in the presence of different cations depending on whether their properties are closely related to those of Ca2+. Labeling by [125I]TID is also observed in the presence of different denaturing agents, and the extent of labeling is reduced by the phenothiazine trifluoperazine. The Ca2+‐dependent exposure of hydrophobic sites was studied for different Ca2+‐binding proteins and evidence is presented that troponin C can be labeled
Resonance Raman spectroscopy shows different temperature‐dependent coordination equilibria for native horseradish and cytochrome c peroxidase
Authors: Evangelista-Kirkup Ruby , Crisanti Mark , Poulos Thomas L. , Spiro Thomas G.
Published: July 2002

Resonance Roman spectroscopy
Horseradish peroxidase
Cytochrome c peroxidase
Coordination equilibrium
Analysis of inactive renin by renin profragment monoclonal antibodies
Authors: Gaillard I. , Fehrentz J.A. , Simon D. , Badouaille G. , Seyer R. , Castro B. , Pau B. , Corvol P.
Published: July 2002

Two peptides were synthesized, corresponding to the sequences (−19 to −7) and (−26 to −17) of the prorenin prosegment. Monoclonal antibodies were raised to these sequences and used to characterize human plasma inactive renin. Only anti (−19 to −7) reacted with inactive renin, as measured by direct assay or affinity chromatography. The data were used to evaluate two possible inactive renin stuctures: (i) plasma inactive renin is a truncated prorenin lacking the prosegment N‐terminal portion; (ii) its spatial conformation masks the N‐terminal extremity, preventing interaction of this region with specific antibodies.
Stopped‐flow spectrophotometry monitoring the initial processes of platelet activation by platelet‐activating factor
Authors: Ohga Yoko , Nakanishi Mamoru
Published: July 2002

The initial processes of platelet activation by platelet‐activating factor (PAF) were observed by stopped‐flow light scattering and fluorometry. The binding of PAF to rabbit platelets did not change the membrane fluidity, though it caused the removal of calcium from internal stores and induced concomitantly platelet shape changes. These results were quite in contrast to those by thrombin and ADP activation, where the membrane fluidity increased before the calcium release from the internal stores. The increased membrane fluidity in the latter system seemed to be used to transmit an external signal to a GTP‐binding protein.
Toxicity of 3‐O‐methyl glucose in yeast is due to its phosphorylation by glucokinase
Authors: Siverio Josè M. , Valdés-Hevía Marta D. , Gancedo Carlos
Published: July 2002

3‐O‐Methyl glucose inhibited the growth of S.cerevisiae on non‐fermentable carbon sources only in strains possessing glucokinase. Accumulation of a phosphorylated derivative of 3‐O‐methyl glucose occurred only in strains carrying glucokinase. Phosphorylation of the sugar in vitro was observed with partially purified preparations of glucokinase but not with equivalent preparations of isoenzymes PI or PII of hexokinase. The K
m value of glucokinase for 3‐O‐methyl glucose was 5 mM and the V
max was ~ of that found for glucose. A mutant resistant to 3‐O‐methyl glucose was isolated from a strain possessing only glucokinase. This mutant had only about 10% of the glucokinase found in the parental strain.
The primary structure of histone H3 from cycad pollen
Authors: Brandt Wolf F. , von Holt Claus
Published: July 2002

The complete primary structure of cycad pollen histone H3 has been established. Microheterogeneity in several positions revealed the presence of H3 variants. Various lysine residues in the N‐terminus were found to be completely or partially methylated. The cycad H3 sequence is compared to that of pea and calf.