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- 저자 : 이현재 ( Kang Wha Kim (검색결과 3 건)
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김강화,이현재,Kang-Wha Kim,Hyun-Jae Lee Korean Chemical Society 1980 대한화학회지 Vol.24 No.4
G. melanogenus로부터 분리한 폴리올 탈수소 효소는 이미 알려진 바의 다른 폴리올 탈수소 효소와는 달리 조효소로서 2,6-dichlorophenolindophenol (DPIP)와 같은 인위적 전자 수용체를 필수로 요구하고 있음으로 이 특수 효소의 반응메카니즘을 반응속도론적 연구를 통하여 규명코저 시도하였으며, 폴리올 산화반응에 대한 초기속도 측정실험과 효소반응 산물인 케토산에 의한 저해 실험을 통하여 이 반응은 Ping-Pong Bi-Bi형의 반응메카니즘으로 진행됨을 확인하였다. 따라서 두 기질 즉 포리올로서 D-mannitol 및 전자수용체로 DPIP가 효소에 의하여 반응이 진행될 경우 D-mannitol이 우선 효소와 작용하며 첫 반응산물로서 해당하는 케토산인 D-fructose가 생성될 것으로 기대되며 이 반응이 전체 반응속도를 조절하는 과정일 것이라고 추측하였다. A steady-state kinetic study on a dye-coupled cytoplasmic polyol dehydrogenase from G. melanogenus was carried by the initial velocity measurements in the direction of the polyol oxidation and the product inhibition by D-fructose. For the initial rate experiments, D-mannitol and D-sorbitol were employed as the specific polyol substrates and 2,6-dichlorophenolin-dophenol (DPIP) as the specific cofactor substrate for the enzyme. When the polyol and DPIP were examined by varying one of substrates and by fixing the second, the corresponding reciprocal plots showed the typical parallel pattern. This suggests that the enzyme from G. melanogenus proceeds by a Ping Pong Bi-Bi mechanism in which the polyol may account as the first reactant-in, and the ketose formed as the first product-out, respectively. The product inhibition patterns obtained by D-fructose (one no-inhibition, one non-competitive, and two competitive) may also provide an additional conformatory evidence for the above mechanism. Based on the kinetic parameters obtained, it was also suggested that the rate-limiting step in the direction of polyol oxidation is associated with the release of the ketose from the Enzyme${\cdot}$Polyol complex.
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Gluconobacter melanogenus 로 부터 새로운 포리올 탈수소 효소의 분리 정제와 효소 특성에 관한 연구
김강화,임옥재,이현재 ( Kang Wha Kim,Ok Jae Im,Hyun Jae Lee ) 생화학분자생물학회 1980 BMB Reports Vol.13 No.3
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.
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김강화,임옥재,이현재,Kim, Kang-Wha,Im, Ok-Jae,Lee, Hyun-Jae 생화학분자생물학회 1980 한국생화학회지 Vol.13 No.3
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.
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