INTERMEDIATE METABOLISM OF AEROBIC SPORES III

Abstract

Cell-free extracts of spores of B. cereus var. terminalis contain glucose dehydrogenase, a system for the direct oxidation of gluconate to 2-keto-gluconate, 2-keto-gluconate kinase, 2-keto-D-gluconate-6-phosphate reductase, a complete hexose monophosphate shunt system, 2-keto-3-deoxy-D-gluconate-6-phosphate aldolase, and a system for pyruvate formation from D-glyceraldehyde-3-phosphate. D-ribose-5-phosphate, ketopentophosphates, sedoheptulose, D-fructose-6-phosphate, and D-glucose-6-phosphate were identified as products of either D-gluconate-6-phosphate or D-ribose-5-phosphate oxidation. A kinetic study of pyruvate formation from 2-keto-D-gluconate-6-phosphate and D-gluconate-6-phosphate suggested that an alternate pathway for 2-keto-D-gluconate-6-phosphate metabolism may be present not involving D-gluconate-6-phosphate as an intermediate. A diphosphopyridine nucleotide linked glucose dehydrogenase was purified by ammonium sulfate fractionation and a triphosphopyridine nucleotide linked D-glucose-6-phosphate dehydrogenase and a diphosphopyridine nucleotide linked D-gluconate-6-phosphate dehydrogenase purified by gradient elution from diethylaminoethyl cellulose columns. Some of the properties of each of these 3 enzymes are described.