Individualité de la D-glucuronate-cétol isomerase d'Escherichia coli K 12

Summary The individuality of uronic isomerase ( D -glucuronate-ketol isomerase) in Escherichia coli K 12, acting on both substrates: glucuronate and galacturonate, and induced either by the first of by the second hexuronate, is demonstrated on the basis of the following results: u — an identical thermostability of the isomerase activity toward either hexuronate and whatever the inducer may be — a constant ratio of purification between both activities measured through the successive steps: protamine sulfate, ammonium sulfate, heat and DEAE-Sephadex chromatography; occurence of a single and homogeneous enzyme peak after chromatography of the mixture of extracts from cells which have been induced by either hexuronate — a single mutation (mapped between arg G and met C ) simultaneously suppresses both activities and their induction by both hexuronates; a reverse mutation restores both activities and their induction by both hexuronates.