Oxidative Metabolism in Pediococcus pentosaceus III. Glucose Dehydrogenase System.

Lee, Chin K. (North Carolina State of the University of North Carolina, Raleigh), and Walter J. Dobrogosz. Oxidative metabolism in Pediococcus pentosaceus. III. Glucose dehydrogenase system. J. Bacteriol. 90:653-660. 1965.-A method was developed for the purification of glucose dehydrogenase from Pediococcus pentosaceus Az-25-5. The procedures included treatments with protamine sulfate, ammonium sulfate, and heat in addition to acid precipitation, calcium phosphate adsorption and elution, and diethylaminoethyl-Sephadex column chromatography. The final preparation thus obtained was purified 255-fold and exhibited both similarities and dissimilarities to the same enzyme isolated from other sources. The enzyme is absolutely specific for nicotinamide adenine dinucleotide phosphate (NADP) as a cofactor, and oxidizes only glucose or its analogue 2-deoxyglucose via the following reversible reaction: beta-d-glucose + NADP right harpoon over left harpoon d-glucono-delta-lactone + NADPH(2) + H(+). K(m) values were 2.3 x 10(-2) for glucose and 2 x 10(-4) for NADP. Monovalent cations were required for stability of the enzyme and stimulated activity. The pH optimum was 7.0, and the equilibrium constant was determined to be 13.4 x 10(-7) at pH 6.4. Among the Lactobacillaceae, glucose dehydrogenase activity was found to be essentially limited to members of the genus Pediococcus. Studies on the enzymatic composition of P. pentosaceus viewed in conjunction with other available data led to the conclusion that this enzyme is not involved to any significant extent in the energy metabolism of this organism.