L-serine deaminating enzymes in Escherichia coli crude extracts

(a) The measured L-serine deaminating activity of a crude bacterial extract may originate from L-serine deaminase, from biosynthetic L-threonine deaminase, or from degradative L-serine deaminase. Nevertheless, the contribution of the individual enzymes can be determined.(b) About a half of the L-serine deaminating activity of wild type E. coli bacteria, grown in synthetic minimal medium, originates from L-serine deaminase and about half from biosynthetic L-threonine deaminase.(c) Ninety percent of L-serine deaminating activity of wild type E. coli bacteria, grown in yeast extract-tryptone medium, originates from L-serine deaminase, and the remainging ten percent from the degradative L-threonine deaminase.(d) Conditions have been established in which threonine deaminases are eliminated and the activity of L-serine deaminase alone could be measured, even in crude extracts.