PMID: 1202696Jan 1, 1975Paper

Study of the regulation of the synthesis and activity of IMP-dehydrogenase in the yeast Pichia guilliermondii

Ukrainskiĭ biokhimicheskiĭ zhurnal
H M Shavlovs'kyĭ, R A Kuznetsova

Abstract

Activity of IMP-dehydrogenase was studied in the cells of P. guilliermondii ATCC 9058 from different growth phase; the yeast was cultivated in iron-rich and iron-deficient media. The highest activity of the enzyme was found in the iron-rich cells from the logarithmic growth phase. In the iron-deficient cells synthetizing great amounts of riboflavin the IMP-dehydrogenase activity was somewhat higher in negative growth acceleration phase than that of iron-rich cells from the same stage. Guanine considerably represses synthesis of IMP-dehydrogenase in the cells of the mutant P. guilliermondii Y-2031 with the blocked GMP-synthetase. In the iron-deficient cells no changes in the character of IMP-dehydrogenase synthesis regulation were found in comparison with the iron-rich cells. 5'-GMP, 5'-GDP and 5'-GTP considerably inhibit IMP-dehydrogenase activity of the cell-free preparations of the yeast P. guilliermondii. 5'-AMP, 5'UMP and 5'-CMP slightly affect the enzyme activity. Guanine inhibits LMP-dehydrogenase activity in experimeents in vivo with the guanine- and arginine-requiring "Y" 2031/arg. Thus, synthesis of guanylic acid in the yeast P. guilliermondii is regulated by means of two mechanisms repression of IMP dehydrogenase synt...Continue Reading

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