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L-Aspartate-alpha-decarboxylase, an enzyme that catalyzes the production of
beta-alanine, has been purified to apparent homogeneity from Escherichia coli.
The properties of the enzyme are: (a) pH optimum of 6.8 to 7.5, (b) temperature
optimum of 55 degrees C, (c) Km for L-aspartate of 0.16 mM, and (d) molecular
weight of 58,000. The activity of the enzyme is inhibited by reagents
(hydroxylamine, phenylhydrazine, and sodium borohydride) that react with
carbonyl groups, but no pyridoxal phosphate is present. The compound containing
the carbonyl group has been identified as covalently bound pyruvate.
Approximately 1 mol of pyruvate was found/mol of enzyme. That the enzyme has a
biosynthetic function rather than a catabolic role is indicated by the
observations that a mutant (designated as E. coli 99-2) which requires either
beta-alanine or pantothenic acid for growth contains only trace amounts of
enzyme activity, whereas it is present in substantial amounts in the parent
strain (E. coli W) and in a spontaneous revertant of the mutant.
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