By the method of microbiological synthesis were obtained and analyzed by electron impact mass-spectrometry 2H, 13C-labeled amino acids of a facultative methylotrophic bacterium Brevibacterium methylicum and an obligate methylotrophic bacterium Methylobacillus flagellatum and 2H, 13C-labeled amino acids of the total protein of biomass obtained on media containing as a source of stable isotopes [2H]methanol, [13C]methanol and 2H2O. It was also performed the incorporation of L- [2,3,4,5,6-2Н]phenylalanine, L-[3,5-2Н]tyrosine and L- [2,4,5,6,7-2Н]tryptopan into the membrane integral protein bacteriorhodopsin synthesised in purple membranes of photoorganotrophic halobacterium Halobacterium halobium ET 1001. For mass-spectrometric analysis the multicomponential mixtures of 2H-and 13C-labeled amino acids, derived from cultural media and protein hydrolysates after hydrolysis in 6 M 2HСl (3% phenol) and 2 M Ва(OH)2 were modified into N-benzyloxycarbonyl-derivatives of amino acids as well as into methyl esters of N-5-(dimethylamino)naphthalene-1-sulfonyl chloride (dansyl) derivatives of [2H, 13С]amino acids, European Reviews of Chemical Research, 2015, Vol.(5), Is. 3 145 which were preparative separated using a method of reverse-phase HCLP. Biosynthetically obtained 2H-and 13C-labeled amino acids represented the mixtures differing in quantities of isotopes incorporated into molecule. The levels of 2H and 13С enrichment of secreted amino acids and amino acid resigues of protein were found to vary from 20,0 atom.% to L-leucine/isoleucine up to 97,5 atom.% for L-alanine depending on concentration of 2H-and 13C-labelled substrates.Keywords: stable isotopes, methylotrophic bacteria, halobacteria, isotope labeled amino acids, bacteriorhodopsin
IntroductionThe enrichment of molecules by stable isotopes (2Н, 13С, 15N, 18O) is an important tool for a variety of biochemical and metabolic studies with amino acids and other biologically active substances (BAS) [1]. The preferential usage of stable isotopes as compared to their counterparts are stipulated by the lack of radioactive radiation hazards and determination of the localization of the label in the molecule by high resolution techniques, including NMR [2], IR spectroscopy [3], and mass spectrometry [4]. The development of these methods for the detection of stable isotopes in biological probes in recent years has significantly increased the efficiency of biological research, as well as studies of the structure and mechanism of action of cellular BAS at the molecular level. In particular, 2H-and 13C-labeled amino acids are used for studying of the spatial structure and conformational changes of proteins, the interaction of protein molecules and in chemical syntheses of some isotope-labeled compounds based on them [5]. For example, isotopically labeled Lphenylalanine is used in the synthesis of peptide hormones and neurotransmitters [6].An important factor in studies using labeled amino acids is their accessibility. 2H and 13C-labeled amino acids can be prepared using ...