Occurrence of the Aldolase and Isomerase Equilibria in Bacterial Metabolism

Abstract

Aldolase and isomerase were shown to be present in a prepn. obtained from Escherichia coli by grinding with powdered glass. The equilibrium is shown to be independent of substrate conc. but dependent on temp. The rate at which the equilibrium point is reached is dependent upon enzyme conc. Mg displaces the equilibrium toward hexo-sediphosphate; NaF and iodoacetic acid are ineffective. Iodine oxidation of triosephosphate obtained from an equilibrium mixture showed that 95% or more of the triosephosphate was dihydroxyacetone phosphate. Similar treatment of triosephosphate isolated by bisulfite addition showed 55% to 70% of the mixture was glyceraldehyde phosphate. The equilibrium was shown, by shifting the temp. and by changing the substrate conc. to be truly reversible. All the evidence obtained indicates that the bacterial enzymes are identical with those in muscle and yeast. The results constitute further evidence of the applicability of the Embden-Meyerhof scheme of glycolysis. in principle, to bacterial dissimilation of carbohydrate.