d -SORBITOL-6-PHOSPHATE DEHYDROGENASE FROM LACTOBACILLUS CASEI

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Abstract
An enzyme which catalyzes the interconversion of sorbitol-6-phosphate and fructose-6-phosphate was purified 14-40 fold from crude extracts of L. casei. The pH optimum for the oxidation lies between 9 and 10. Di-(DPN) but not triphosphopyridine nucleotide serves as coenzyme. The enzyme possesses essential sulfhydryl groups and is inactivated by Hg++, Zn++ and Cu++. No evidence was obtained for a metal requirement. The approximate equilibrium constant for the reaction was 1.07 x 10-9. Michaelis constants for substrate and DPN were 2.5 x 10"5 [image] and 5.4 x 10-5 [image] respectively.