Alkema, D., see P. A. Hader 136 (1981) 65 arachidonic acid by rabbit neutrophils 136 (1981) 293 Amons, R., see A. T. Gudkov 136 (1981) 235 Bowers, W. E., see E. H. Harrison 136 (1981) 289 Anzai, H., see F. Kawamura 136 (1981) 244 Braznlkov, E. V., see D. A. Dolgikh 136 (1981) 311 Appelt, K., see M. Kimura 136 (1981) 58 Brethes, D., see C. Garret 136 (1981) 216 Arad, G. and T. J. C. Beebee, Measurement Burdge, E. L. and K. G. Wilson, Regulation of 5 S RNA accumulation in oocytes of of the aspartate pathway in isolated Xenopus laevis using a cDNA probe 136 (1981) 247 pea chloroplasts: Effects of S-2-aminoArseniev, A. S., Yu. N. Utkin, V. S. Pashkov, ethylcysteine and threonine on the V. I. Tsetlin, V. T. Ivanov, V. F. Bystrov metabolism of labeled aspartate and Yu. A. Ovchinnikov, 19F NMR deter136 (1981) 322 Burmeister, M., see P. Graber 136 (1981) 25 mination of intramolecular distances in Bystrov, V. F., see A. S. Arseniev 136 (1981) 269 spinand fluorine-labelled proteins: Bychkova, V. E., see D. A. Dolgikh 136 (1981) 311 Neutrotoxin II Naja naja ox&a 136 (1981) 269 Avigliano, L., J. L. Davis, M. T. Graziani, Carrillo, N., see R. Wagner 136 (1981) 208 A. Marchesini, W. B. Mims, B. Mondovi Charriaut, C., see M. Bare1 136 (1981) 111 and J. Peisach, Electron spin echo specChevallier, J., see C. Garret 136 (1981) 216 troscopy studies of type 1 and type 2 Christen, P., see H. Wacker 136 (1982) 329 copper in Rhus vernicifera lactase and Ciudad, C. J., see M. A. Mor 136 (1981) 131 in Cucurbita pepo medullosa ascorbate Claesson, H.-E., see S. J. Feinmark 136 (1981) 141 oxidase 136 (1981) 80 Clore, G. M., see A. M. Gronenborn 136 (1981) 160 Cohen, P., see A. Morel 136 (1981) 316 Bandman, E., R. Matsuda, J. MicouCook, G. M. W., see N. G. Rutherford 136 (1981) 105 Eastwood and R. Strohman, In vitro translation of RNA from embryonic and Contencas, P., see C. Rodrigues-Pousada 136 (1981) 239 Costa, J. L., C. M. Dobson, D. D. Fay, K. L. from adult chicken pectoralis muscle Kirk, F. M. Poulsen, C. R. Valeri and produces different myosin heavy chains 136 (1981) 301 J. J. Vecchione, Nuclear magnetic resoBarel, M., C. Charriaut and R. Frade, Isolanance studies of amine storage in pig tion and characterization of a C3b recepplatelets 136 (1981) 325 tor-like molecule from membranes of a Cottin, P., P. L. Vidalenc and A. Ducastaing, human B lymphoblastoid cell line (raji) 136 (1981) 111 Ca*+-Dependent association between a Baudras, A., see A. M. Gronenborn 136 (1981) 160 Ca”-activated neutral protelnase Baumann, C. M. and H. Riidiger, Interac(CaANP) and its specific inhibitor 136 (1981) 221 tions between the two lectins from Vi& Cousineau, C., see J. Sinclair 136 (1981) 213 cracca 136 (1981) 279 Cox, R. A. and J. M. Kelly, A study of the Becker, E. L., see B. J. Bormann 136 (1981) 293 arrangement of 18 S rRNA within 40 S Beebee, T. J. C., see G. Arad 136 (1981) 247 subparticles of rabbit ribosomes 136 (1981) 306 Bell, R. A., see D. Alkema 136 (1981) 70 Bennoun, P., Does the chloroplast control D’Alagni, M. de Petris and G. B. Marinimitochondrial functions? 136 (1981) I Bettolo, On the interaction between Ben-Zeev, O., H. Schwalb and M. C. Schotz, Jatrophone and DNA 136 (1981) 175 Interaction of two fractions of heart Dautrevaux, M., see S. Djoumessi 136 (1981) 145 lipoprotein lipase with natural and synDavis, J. L., see L. Avigliano 136 (1981) 80 thetic substrates 136 (1981) 95 Djoumessi, S., J. Rousseaux and M. Blbkberg, L., D. Lombardo, 0. Hernell, Dautrevaux, Structual studies of a new 0. Guy and T. Olivecrona, Bile salthemoglobin: HbJ Lens, p13(AIO) stimulated lipase in human milk and Ala -+ Asp 136 (1981) 145 carboxyl ester hydrolase in pancreatic De Boer, P. A. J., see A. F. M. Moorman 136 (1981) 45 juice: Are they identical enzymes? 136 (1981) 284 De Laaf, R. T. M., see A. F. M. Moorman 136 (1981) 45

α‐Conotoxins are small peptides from cone snail venoms that function as nicotinic acetylcholine receptor (nAChR)‐competitive antagonists differentiating between nAChR subtypes. Current understanding about the mechanism of these selective interactions is based largely on mutational analyses, which identify amino acids in the toxin and nAChR that determine the energetics of ligand binding. To identify regions of the nAChR involved in α‐conotoxin binding by use of photoactivated cross‐linking, two benzoylphenylalanine (Bpa) analogs of α‐conotoxin GI, GI(Bpa12) and GI(Bpa4), were synthesized by replacing the respective residues with Bpa, and their 1H‐NMR structures were determined. Both analogs preserved the GI conformation, but only GI(Bpa12) displaced 125I‐labeled GI from the Torpedo californica nAChR. 125I‐labeled GI(Bpa12) bound to two sites on the receptor (Kd 13 and 1800 nm), and on UV irradiation specifically photolabeled the α, γ and δ subunits. Photolabeling sites were mapped by selective proteolysis and enzymatic deglycosylation, combined with SDS/PAGE, HPLC and Edman degradation. In the α subunit, cobratoxin‐inhibited incorporation was limited to the 22‐kDa fragment beginning at αSer173 and containing the agonist‐binding site segment C. In the γ subunit, radioactivity was localized to two distinct peptides containing agonist‐binding site segments F and D: nonglycosylated 24‐kDa and glycosylated 13‐kDa fragments starting at γAla167 and γAla49, respectively. The labeling of these fragments is discussed in terms of a model of GI(Bpa12) bound to the extracellular domain of the Torpedo nAChR homology model derived from the cryo‐electron microscopy structure of Torpedo marmorata nAChR and X‐ray crystal structures of snail acetylcholine‐binding protein complexes with agonists and antagonists.

It was previously shown that the catalytic subunit of the plant toxin viscumin induces aggregation of small unilamellar liposomes and this process is inhibited by the mab_TA7 monoclonal antibody produced to the denatured catalytic subunit of viscumin (Agapov, I.I. et al. , FEBS Lett. , 1999, vol. 464, p. 63). The interaction of the synthetic F 101 –T 105 and A 96 –T 105 fragments of the viscumin catalytic subunit with the mab_TA7 monoclonal antibody was studied by 1 H NMR spectroscopy. Results of this study demonstrated that only the A 96 –T 105 fragment is capable of binding to mab_TA7. A nuclear Overhauser effect observed in the antigen–antibody complex and registered on the resonances of the free peptide transferred from the free state to the antibody-bound state was analyzed, the mab_TA7 antigen determinant (H 99 –T 105 ) was identified, and its conformation and orientation within the complex with the antibody were determined.

The plant toxin viscumin (60 kD) consists of B- (“binding”) and A- (“active”) subunits joined by a disulfide bond. The B-subunit is a lectin interacting with galactose-containing glycolipids and glycoproteins of the cell surface. The A-subunit possesses N-glycosidase activity which modifies 28S ribosomal RNA. This results in irreversible inhibition of protein synthesis. After binding and receptor-mediated endocytosis viscumin-containing vesicles are transported to endoplasmic reticulum where the A- (catalytic) subunit is subsequently translocated to cytosol. It is possible that translocation of A-subunit requires its unfolding. For identification of epitopes which might appear during such unfolding, we developed hybridomas producing monoclonal antibodies against denatured viscumin A-chain. Resistance of hybridoma cells to cytotoxic action of viscumin suggests antibody–toxin interaction inside these cells. TA7 hybridoma cells against an epitope which appears only in denatured viscumin are insensitive to the toxin. This suggests that antibody–toxin interaction occurs before transmembrane translocation of the catalytic A-chain into the cytoplasm. Consequently, toxin resistance of TA7 hybridoma cells implies the appearance of a new epitope in viscumin during its intracellular transportation inside of vesicles. Sixty five octapeptides have been synthesized and epitopes have been identified for monoclonal TA7 antibody and immune mouse serum by means of ELISA. Based on the epitopic mapping the peptide A96-ETHLFTGT-T105 was chemically synthesized and binding of this peptide to the monoclonal antibody TA7 and conformation of antigenic determinant (L100-FTGT-T105) was investigated by means of 1H-NMR spectroscopy.

Effect of the monoclonal antibody (MAb) 5B6 produced to the solubilized preparation of bacteriorhodopsin on the protein photocycle was studied to examine conformational rearrangements on the surface of a functioning bacteriorhodopsin molecule. Using solid phase enzyme immunoassay, peptide phage display, and 1 H NMR spectroscopy, we demonstrated that the epitope recognized by MAb 5B6 is the Val69-Pro-Phe-Gly72 fragment of the protein, with the aromatic ring of Phe71 and the methyl groups of Val69 participating in the binding. MAb 5B6 exerted no significant effect on the photocycle of bacteriorhodopsin solubilized in Triton X-100 at pH 6.2 and 7.4 which suggested that, when functioning, bacteriorhodopsin retains the conformation and position of its Val69-Pro-Phe-Gly72 fragment.

Identification of two new eapsid proteins in bacteriophage M13, G. F. M. Simons, R. N. H. Konings, J. G. G. Schoenmakers 8 Arachidonic acid-dependent metabolism of 7,8-dihydroxy-7,8-dihydro-benzo [a]pyrene by ram seminal vesicles, L. J. Marnett, J. T. Johnson, M. J. BienkowsM 13 Arachidonic acid-dependent metabolism of (-+) trans-7,8-dihydroxy-7,8-dihydrobenzo [a]pyrene (BP-7,8 diol) to 7,10/8,9 tetrols, K. Sivara]ah, H. Mukhtar, T. Eling 17 Amphopteriein B has very different effects on the glucagonand fluoride-stimulated adenylate cyclase activities of rat liver plasma membranes, L Dipple, M. D. Houslay 21 Differential effects of dirnethylsulfoxide on S-adenosylmethionine synthetase from rat liver and hepatoma, G. Okada, Y. SawaL H. Teraoka, K. Tsukada 25 Phosphorylation coupled to H 2 oxidation by chromatophores from Rhodopseudomonas capsulata, F. Paul, A. Colbeau, P. M. Vignais 29 The role of the Calvin cycle for anoxygenic CO 2 photoassimilation inAnacystis nidulans, G. A. Peschek 34 Thermostable single-band cytochrome oxidase, N. Sone, T. Ohyama, Y. Kagawa 39 Influence of tungstate on the formation and activities of four reductases in Proteus mirabilis. Identification of two new molybdo-enzymes: chlorate reductase and tetrathionate reductase, L. F. Oltmann, V. P. Claassen, P. Kastelein, W. N. M. Rei]nders, A. H. Stouthamer 43 EPR and fluorescence study of interaction ofNa]a na]a oxiana neurotoxin II and its derivatives with acetylcholine receptor protein from Torpedo marmorata, V. L Tsetlin, E. Karlsson, A. S. Arseniev, Yu. N. Utkin, A. M. Surin, V. S. Pashkov, K. A. Pluzhnikov, V. T. Ivanov, V. F. Bystrov, Yu. A. Ovchinnikov 47 Electric breakdown of bilayer phospholipid membranes under ultraviolet irradiationinduced lipid peroxidation,A. V. Putvinsky, A. L Sokolov, D. L Roshchupkin, Yu. A. Vladimirov 53 Evidence for nonhistone chromosomal protein kinase activity associated with nucleosomes isolated from HeLa S s cells, L R. Phillips, E. A. Shephard, W. B. Tatcher, J. L. Stein, G. S. Stein 56 Interaction of the tRNA-derived unusual nucleoside, t6A with Mn(II) and Mg(II), R. P. Reddy, M. P. Schweizer, G. B. Chheda 63 Microtubule proteins in the yeast, Saccharomyces cerevisiae, L. Clayton, C. L Pogson, K. Gull 67 Type V collagen: Possible shared identity of c~A, c~B and c~C chains, R. A. Brown, J. B. Weiss 71 Studies on the structural requirements of a microsomal cAMP-independent protein kinase, F. Meggio, A. Donella-Deana, L. A. Pinna 76

Desmosome-like contacts (DLC) in afferent chemical synapses of the Mauthner cells (MC) were investigated after application of low and high molecular mass peptide fractions 6 and 9, correspondingly, from the Central Asiatic black scorpion Orthochirus scrobiculosus. Besides, the DLC were examined in condition of a training induced morpho-functional stability of the MC (adaptation) mediated by transformation of actin monomers into polymers. In addition, the structure of DLC was studied after cytochalasin application which disrupts F-actin. Fraction 6 was shown to increase the length of DLC and osmiophily of fibrous material. Similar changes in DLC were caused by adaptation. Fraction 9 decreased the osmiophily of the fibrous material, made DLC asymmetric, but did not influence their length. Similar changes in DLC were seen also after cytochalasin D application. Taking into account our previous data on the role of F-actin in the MC functioning, which were obtained following specific pharmacological treatments, the similarity of ultrastructural changes in DLC after both adaptation and fraction 6 application, on the one hand, and after both cytochalasin D and fraction 9 application, on the other one, enabled us to suggest that these fractions may contain peptides able to exert influence of the actin cytoskeleton.

The results of comparative measurements of annihilation rate coefficients of fluorine radicals (K-a) are presented. These results are obtained by means of three modifications of time-resolved actinometry:1. by conventional techniques with square pulse delay time variation in a full discharge power modulation mode;2. with partial discharge power modulation by square pulses; and3. with full discharge modulation by a series of short pulses in the afterglow stage.Intensity microchronograms of spectral lines of F radicals (703.7 nm); Ar (750.4 nm) and their background values (701.7 and 748.4 nm) were obtained by means of a dedicated time-resolved (2.5 mu s) acousto-optic spectrometer. The spectral resolution was equal to 0.35 nm. Fluorine radicals' kinetic annihilation curves were deduced by processing the measured chronograms according to the basic actinometry equation. K-a values were determined from exponential decay tits of the dropping parts of the kinetic curves. In addition, in the first of the above-mentioned modifications, a residual concentration level was used in an integral expression for the reactive particle concentration at the annihilation stage. The importance of this parameter was shown in earlier papers. (C) 1999 Elsevier Science S.A. All rights reserved.

A synthetic peptide corresponding to the transmembrane segment M2 (residues 236-267) of the alpha-subunit of the nicotinic acetylcholine receptor from Torpedo californica has been studied by two dimensional 1H-NMR spectroscopy in a chloroform-methanol (1:1) mixture containing 0.1 M LiClO4. Reconstruction of the spatial structure of M2 from the NMR data resulted in an alpha-helix formed by residues 241-263. Distribution of the molecular hydrophobicity potential on the helix surface is very similar to that in five-helix bundles of proteins with a known three dimensional structure: two hydrophilic bands located on the opposite helix sides separated by strong hydrophobic zones.

A method of emission actinometric measurement of kinetic parameters of plasmachemical reactions is proposed including the determination of the kinetic order, annihilation rate constants of chemically active particles and their characteristic lifetimes. The basis of the method is the time-resolved actinometry and the discharge power modulation by a probing pulse series at the afterglow stage with a time resolution of Delta t greater than or equal to 1 mu s. Kinetic accumulation and annihilation curves at this stage are derived from the microdynamics of spectral line intensitities of the selected actinometric pairs, The measurements of spectral line peaks and their background values controlled by the PC microcomputer are carried out at four to nine wavelengths in a quasi parallel mode of an acoustooptic spectrometer. The duration of a measurement cycle of 100 repeated measurements al four wavelengths with a time resolution of 25 mu s took no more than 50 s. The values of kinetic parameters can be derived from the analysis of the logarithmic plot of the kinetic curve of particle annihilation.Measurements of the heterogeneous annihilation rate constant for atomic fluorine have been carried out in the SF, RF plasma with an addition of argon as an actinometer in a standard diode-type Al-reactor. The values of pulse length and duty cycle of probing pulses are determined experimentally for measuring the kinetic parameter of fluorine annihilation in such a way that there is no substantial increase of the fluorine residual concentration level. Based on the analysis of the experimental kinetic curve of heterogeneous annihilation, a solution taking into account a procedural error of the proposed method due to nonzero level of the residual concentration of the observed particles at the afterglow stage is proposed, The experimentally obtained value of the fluorine heterogeneous annihilation rate constant measurement error is about (15 +/- 2)% at a residual concentration level of about 10%.The measurement reproducibility of fluorine heterogeneous annihilation rate constant is 3-5% in the unloaded and silicon wafer loaded reaction chamber with actinometer concentrations of 2.5 and 5.6%. (C) 1998 Elsevier Science S.A.

Interaction of the monoclonal antibody A5 raised against native bacteriorhodopsin (BR) with the synthetic peptide pGlu1-Ala-Gln-Ile-Thr-Gly-Arg7-NH2, corresponding to the amino acid sequence 1-7 was studied by transferred nuclear Overhauser effect (TRNOE) spectroscopy. The denaturing reagents and the specially designed pulse sequences which eliminate broad signals from the TRNOE spectra were used to favour evaluation of the TRNOE peaks. On the basis of the data obtained, the conformation of peptide bound with A5 was calculated. A model of the mutual arrangement of bacteriorhodopsin N-terminus and the first transmembrane alpha-helical segment 8-32 was proposed.

Proton signals for nine synthetic peptide fragments of human interleukin-2 (region 59-78) were assigned for aqueous solutions both of pure peptides and their mixtures with LNKB-2 monoclonal antibody. The nonspecific magnetization transfer (NOE) between the antibody or its Fab-fragment and the peptides was studied upon large excess of free peptide over bound peptide. NOE spectra using modified pulse sequence, enabling to eliminate broad signals and achieve higher (peptide signal)/noise ratio were obtained. The saturation transfer experiments indicated that methyl groups of amino acid residues corresponding to Leu66,70,72, Val69 and Ala73 in interleukin-2 contact with the antibody binding site. Thus, the hydrophobic interactions are of major importance for the LNKB-2-IL-2 peptide complexes. The minimal IL-2 fragment which can still bind to LNKB-2 monoclonal antibody is -Leu70-Asn71-Leu72-.

Neurotoxin M9 isolated from the venom of Central Asian scorpion Buthus eupeus (66 amino acid residues, 4 disulfide bridges) has two slowly exchangeable conformations at the acidic pH. 2D-1H-NMR spectroscopy has been used to determine the polypeptide backbone foiding in the conformer that dominates under physiological conditions. The conformer contains the right alpha-helix (residues 22-31) and the antiparallel beta-sheet, which consists of the three strands (residues 1-5, 46-52, 35-40). All five Xxx-Pro bonds are in the trans configuration. Comparison of the obtained data with the crystal structure of the homologous scorpion toxin v-3 Centruroides sculpturatus (65 residues) and the solution spatial structure of the "short" type insectotoxin I5A Buthus eupeus (35 residues) shows close similarity in the first case and similarity of the types and mutual disposition of the regular secondary structure elements in the second case.

In 1H NMR spectra of neurotoxin II N. n. oxiana the chemical shift pH-dependences in H2O and 2H2O solutions were studied, and also the deuterium exchange rates and chemical shift temperature gradients were measured for the amide protons. The spin probe method was applied to assess the degree of exposure into solvent of the amide and side chain protons. With the purpose of establishing mutual disposition of certain neurotoxin II groupings, nuclear Overhauser effect was studied in the 1H NMR spectra, along with the broadening of proton resonances induced by spin labels selectively attached to epsilon-amino groups of Lys26, Lys27, Lys45 or Lys47. The mobility of these labels was determined from the EPR spectra. The methyl resonances of Val and Leu residues were assigned to a definite position in the amino acid sequence. The following pKa were determined: alpha-NH2 Leu1 (9,2), gamma-COOH Glu2 (3,7), alpha-COOH Asn62 (1,3). The protonation of a carboxyl group(s) in neurotoxin II (alpha-COOH Asn62 seems to be involved) decreases the temperature stability of the neurotoxin II conformation. On the basis of studies on neurotoxin II and some other homologous neurotoxins, the model for the "short" neurotoxin folding in solution was proposed. Comparison of experimental data for the disposition of equivalent groups in homologous neurotoxins and in the X-ray structure of erabutoxin b Laticauda semifasciata revealed that the Val46 side chain in solution might change its orientation by 180 degrees with respect to polypeptide backbone. Binding of spin labeled neurotoxin II derivatives to the acetylcholine receptor was discussed in light of the obtained data.

After neurotoxin II Naja naja oxiana reaction with N-hydroxysuccinimidyl 2,2,6,6-tetramethyl-4-carboxymethylpiperidine-1-oxyl, six derivatives were isolated, each containing one spin label. Their analysis (reduction, carboxymethylation, tryptic hydrolysis, isolation and identification of the spin labeled peptide) allowed to localize the label position: the epsilon-amino groups of Lys15, Lys25, Lys26, Lys44, Lys48, and alpha-amino group of Leu1. The neurotoxin II reaction with N-hydroxysuccinimidyl 2,2,5,5-tetramethyl-3-carboxypyrrolin-1-oxyl followed by chromatography afforded 10 derivatives, each having two labeled lysine residues, wherein the position of the modified residues was determined. The reactivity and microenvironment of amino groups are discussed basing on the dependence between the reaction conditions and yields. For di-spin labeled derivatives of the pyrroline series, the inter-label distances were determined by EPR from the standard curve and used for refinement of the neurotoxin conformation in solution.

Fifteen Naja naja oxiana neurotoxin II derivatives mono and di spin-labeled on Lys-15, Lys-25, Lys-26, Lys-44 and Lys-46 have been prepared and the position of the label(s) identified. Spin label distances to a number of the side chains were determined by 1H NMR for the mono-labeled species and interlabel distances were determined by EPR for the di-labeled residues. Binding of the mono spin-labeled derivatives to solubilized acetylcholine receptor protein (AChR) from Torpedo marmorata was followed by EPR. By means of a spin probe technique, it was found that spin labels on Lys-15, Lys-25, Lys-46 and, especially Lys-26, are less accessible in the AChR complexes than in the free toxins. Involvement of the dansyl labels on Lys-26 and Lys-46 in the binding was demonstrated by fluorescence spectroscopy. The data obtained yielded evidence of a β-structure of the toxin and allowed preliminary characterization of the neurotoxin binding surface.