"Methylotrophic biomass as 2H-labeled substrate for biosynthesis of inosine"
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The presence of peak corresponding to the hypoxantine fragment [C5H4ON4]+ at m/z 138 (instead of m/z 136) and the peak of sugar fragment [C5H9O4]+ at m /z 136 (instead of m/z 133) proved that two deuterium atoms are located in hypoxantine, however, three of them are attributed to the ribose pattern. Fig.3 Mainly two aspects of the enrichment of inosine were taken into account (scheme). First, because protons in С’1-С’5 positions of ribose pattern in inosine could be originated from glucose,
we assumed, that the character of biosynthetic enrichment of deuterium in sugar pattern of inosine is determined mainly to the functioning of a number of processes of hexose monophosphate shunt of glucose assimilation. But since protonated glucose was added in growth medium, its contribution in the inosine enrichment was minimal. Nevertheless, the results suggested, that ribose contained three deuterium atoms that could not stemp from glucose. Three deuterium atoms probably stemp via some minor reactions of
glucose biosynthesis. Secondly, the numerous exchange processes and intermolecular regrouping reactions, occurring with participation of 2H2O could also be resulted in specific labelling of inosine. Such accessible positions are occupied by the easily exchangeable hydrogen (deuterium) atoms both of hydroxylic- and imino groups of inosine. Two protons at C-H positions in inosine could be replaced by deuterium via assimilation of 2H-labeled hydrolysate.
The enrichment of inosine was approximately the same as 2H2O content in growth medium (65.5-67.5%). LITERATURE. 1. Munch-Petersen A (1983) Metabolism of nucleotides, nucleosides, and nucleobases in microorganisms. Academic Press. Inc New York. 105. 2. Wuthrich K. (1986) NMR of proteins and nucleic acids. New York: J. Wiley & Sons. 14. 3. Bloch A. (1975) Chemistry, biology, and clinical uses of nucleoside analogs.Скачать сочинение