Partial amino acid sequence of gamma-46 gliadin.

We have determined the partial amino acid sequence (207 amino acids) of gamma-46 gliadin isolated from wheat cultivar Hardi. The molecular mass of the protein (Mr) estimated by electrospray mass spectrometry is 35191.3. The number of cysteine residues in gamma-46 gliadin was determined as a mass difference of the protein before and after reduction and alkylation with 4-vinylpyridine. It was shown that the protein has no free SH-groups, and all cysteine residues are involved in the formation of four disulfide bonds. The partial structure of gamma-46 gliadin was determined by N-terminal sequencing and sequencing of tryptic and chymotryptic peptides. The tryptic peptides were obtained by enzymatic hydrolysis of the protein, which was preliminarily reduced and immobilized at free SH-groups on thiopropyl-Sepharose 6B. The chymotryptic peptides were isolated by limited digestion of the native protein. The positions of cysteine residues, as well as surrounding amino acid sequences, are conserved in gamma-46 gliadin; this is typical of gliadins.

Structural characterization of extracellular ribonuclease of Bacillus polymyxa: amino acid sequence determination and spatial structure prediction.

The primary structure of extracellular Bacillus polymyxa ribonuclease (RNase Bpo) was established by mass spectroscopy analysis and automatic Edman degradation of the individual peptides obtained from protein digestion with Glu-specific protease V8. RNase Bpo consists of 111 amino acid residues, with a relative molecular weight of 12 607. RNase Bpo is a close structural homolog of RNases of B. amyloliquefaciens (RNase Ba) and B. intermedius (RNase Bi), the similarity of their primary structures being 68%. Molecular modelling of the structure of the complex of RNase Bpo with substrate analog d(CGAC) was performed and a spatial model based on the known crystal structure of RNase Ba complex with the corresponding nucleotide was constructed using the methods of interactive computer graphics and energy minimization. The differences in the primary and tertiary structures of the enzymes were analyzed in order to understand the substrate specificity of Bacillus RNases.

Mass-spectrometric analysis of N-acetylchitooligosaccharides prepared through enzymatic hydrolysis of chitosan.

A semipreparative scale chromatography of N-acetylchitooligosaccharides (GlcNac)2-7 on a reversed-phase C-16 HPLC column is reported. The initial material was obtained by enzymatic hydrolysis of chitosan with a complex of chitinases from Streptomyces kurssanovii, followed by a complete acetylation of amino groups. Isolated N-acetylchitooligosaccharides were characterized by the mass-spectrometric method. On interacting with the sample, the fragments of 252Cf caused desorption of quasi-molecular ions of the substance. All mass spectra of chitin oligomers contained intense quasi-molecular ions [M + Na]+ and a less intense [M + K]+ ion. Fragment ions, compared to the quasi-molecular ion [M + K]+, had a lower intensity and confirmed the structure of samples under study. Due to this phenomenon, an accurate analysis of both individual compounds and mixtures of N-acetylchitooligosaccharides (n = 2-7) may be performed.

[Identification of the N-terminal peptide of bovine tryptophanyl-tRNA-synthetase]. / Identifikatsiia N-kontsevogo peptida bych'ei triptofanil-tRNK-sintetazy.

By means of covalent chromatography on thiopropyl-sepharose 6B the N-terminal, as well as other tryptic cysteine-containing peptides of the bovine tryptophanyl-tRNA-synthetase (EC 6.1.1.2) were purified and characterized, their structures being determined by a combination of plasma desorption mass spectrometry and peptide sequencing. In total, six different peptides containing seven cysteine residues were analysed. The N-terminal amino acid (presumably, alanine) was shown to be acetylated in the nature enzyme amino acid sequences of some cysteine-containing peptides proved to differ from those deduced from the cDNA structure, thus indicating the presence of the enzyme's isoforms. The purification does not affect the peptides' sulfhydryl groups. The number of cysteine residues in the peptides could be determined with a high accuracy by measuring their masses before and after alkylation with 4-vinylpyridine.

[Two forms of extracellular low molecular weight Bacillus sp. BCF 247 ribonuclease. Isolation and characteristics of the protein]. / Dve formy vnekletochnoi nizkomolekuliarnoi ribonukleazy Bacillus sp. BCF 247. Vydelenie i kharakteristika belka.

Two homogeneous samples of low molecular mass RNAase (RNAases Bci I and Bci II) were obtained from cultural filtrates of spore-forming bacteria strain Bacillus sp. BCF 247 isolated from permafrost soils. The yields of RNAases Bci I and Bci II were 17% and 16% at the 17388- and 15376-fold degree of purification, respectively. Both enzymes have a close specific activity which is equal to approximately 4.7 x 10(-5) activity units per mg of protein. The relative molecular masses of the isolated proteins were determined and their N-terminal amino acid sequences identified. It was shown that the higher molecular mass sample of the enzyme is a pro-RNAase which, in contrast with the mature protein, contains an additional decapeptide segment in the N-terminal part of its molecule. The structure of RNAase Bci was compared with that of RNAases obtained from other Bacillus species; its ability to interact with a natural intracellular inhibitor of B. amyloliquefaciens RNAase was demonstrated.

[Ionization energy and glycoside bond rupture energy of nucleosides, suppressing the reproduction of the human immunodeficiency virus (HIV)]. / Energii ionizatsii i énergii razriva glikozidnoi sviazi nukleozidov, podavliaiushchikh reproduktsiiu virusa immunodefitsita cheloveka (VICh).

By photoionization mass spectrometry the energy characteristics were investigated for a series of nucleosides whose triphosphates possess anti-HIV activity. The electron-donor ability (a value reciprocal to ionization energy) does not correlate with the biological activity of corresponding nucleotides. The energy of glycoside bond rupture depended on modification in deoxyribose.

[Study of energy characteristics of 5-fluorouracil analogs by photoionization mass-spectrometry]. / Izuchenie énergeticheskikh kharakteristik proizvodnykh 5-ftoruratsila metodom fotoionizatsionnoi mass=spektrometrii.

The fragmentation pathways of N-1-alkoxyalkyl derivatives of 5-fluorouracil and various analogues of an antitumor drug ftorafur have been examined using a mass-spectrometry technique. The ionization and appearance energies for major ions of the compounds under study have been determined on the basis of the ionization efficiency curves obtained using photoionization mass-spectrometry. Different transport forms of 5-fluorouracil have been demonstrated to be similar in the stability of their pseudoglycosidic C-N bond.