d -Alanine Oxidase from Escherichia coli : Localization and Induction by l -Alanine

Abstract

Dialyzed membranes of Escherichia coli prepared by an ethylenediaminetetraacetic acid-lysozyme method catalyze the oxidation of both l -alanine and d -alanine. The specific activities for the oxidations of both d -alanine and l -alanine are increased fivefold when the cells are grown in the presence of either l -alanine or dl -alanine, but are increased only slightly when grown in the presence of d -alanine. In the dl -alanine-induced system, the specific activities for the oxidations of some other d -amino acids are also raised. dl -alanine also induces two other alanine catabolizing enzymes, alanine dehydrogenase and alanine-glutamate aminotransferase which are found in the “soluble” fraction of lysozyme-treated cells. The oxidations of both l -alanine and d -alanine were associated with the membranes of induced cells. After the membranes were disintegrated by sonic treatment, both l -alanine and d -alanine oxidation catalysts sedimented in a sucrose density gradient together with d -lactate and l -lactate dehydrogenases, apparently as a single multienzyme complex.