초산박테리아 속의 하나인 G. melanogenus로부터 새로운 포리올 탈수소효소를 얻어 정제하였으며, 이 효소의 특성을 연구 검토해 본 결과 이 효소는 지금까지 알려진 바의 포리올 탈수소효소와는 달리 조효소로서 $NAD^+$나 $NADP^+$ 등을 필요로 하지 않는 대신 2, 6-dichlorophenolindophenol(DPIP)와 같은 인위적인 전자 수용체와 직접 연결되어 있음을 알았다. 한편 효소의 기질 특이성에 있어서도 D-Mannitol과 D-Sorbitol 같은 D-lyxo 형의 구조를 갖는 포리올에 대하여만 특이하게 작용하여 산화적 촉매 활성도를 보임으로서 해당하는 케토산인 D-Fructose와 L-sorbose를 생성시킴을 알았다. 그밖에도 본연구에서는 이 새로운 효소의 일반적 특성 즉, 효소의 안정도, 최적활성도 및 기질에 대한 친화력 등에 대하여도 검토하였으며. 이 효소의 생리적 본질에 대하여 서로 고찰해 보았다.
A new form of the cytoplasmic polyol dehydrogenase having a distinct cofactor and substrate specificity was isolated from the cell free extracts of the sorbitol grown cells of G. melanogenus, and purified partially by CM-cellulose and Sephadex G-100 columns. The enzyme was found to be acted as a typical polyol dehydrogenase catalyzing the oxidation of the polyols to the ketoses, but unlike the other known cytoplasmic dehydrogenases, its catalytic activity was demonstrated only in the presence of an artificial electron acceptor like DPIP. The enzyme did not showed any requirement of pyridine nucleotide coenzymes, nor the molecular oxygen for the polyol oxidation. In the presence of DPIP, however, the enzyme was active and showed a very limitted substrate specificity toward the polyols having D-lyxo configuration such as D-mannitol and D-sorbitol. The $K_m$ values for the tested polyol substrates were found to be about $10^{-1}M$, and the optimum enzyme activity was obtained at pH 5.5. Stoichiometric composition of the polyol and DPIP for this enzyme catalyzed reaction showed a linear quantitative relationship between the rates of the ketose formation and the DPIP reduction. The characteristic mode of the enzyme action was also studied by some kinetic and inhibition experiments with several substrate analogues.
