ACTIVITIES OF CERTAIN AMINOTRANSFERASES AND NADP-DEPENDENT GLUTAMIC ACID DEHYDROGENASE IN YEAST DURING FERMENTATION

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Abstract
The activities of alanine (E.C.2.6.I.2.), aspartate (E.C.2.6.I.I) and glycine (E.C. 2.6.I.4) aminotransferases and NADP-dependent glutamic acid dehydrogenase (E.C.I.4.I.4) have been followed in Saccharomyces cerevisiae during fermentation in an all-malt wort. The synthesis of alanine aminotransferase is enough to furnish the yeast with alanine, but glycine aminotransferase activity is inadequate for glycine requirements during the fermentation period when glycine and alanine are not assimilated from the medium. The synthesis of all four enzymes is repressed to various extents during the early stages of fermentation, but de-repression occurs towards the end of the fermentation.