L - Glycerol - 3 - Phosphate Dehydrogenase 에 관한 연구 ( Ⅳ ) 사람 태반의 α - Glycerophosphate Dehydrogenase = Studies on L - Glycerol - 3 - Phosphate Dehydrogenase ( Ⅳ ) Alpha - Glycerophosphate Dehydrogenase from Human Term Placenta

다국어 초록 (Multilingual Abstract)

Alpha-glycerophosphate dehydrogenase of human term placenta has been studied. Human term placenta was fractionated by differential centrifugation into cytoplasmic and mitochondria fractions. The activity of cytoplasmic α-glycerophosphate dehydrogenase (G3P: NAD 2-oxidoreductase, EC 1. 1. 1. 8) was assayed according to the method of Gonzalez-Cerozo and the activity of mitochondrial α-glycerophosphate dehydrogenase(G3P: cytochrome oxidoreductase, EC 1. 1.99.5) was determined by the procedure of Dawson and Thorne. Partial purification of NAD-linked α-glycerophosphate dehydrogenase was acheived by ammonium sulfate precipitation, Sephadex G-100 and DEAE-cellulose column chromatography, and the properties of the enzyme were studied. The results obtained are as follows: 1. Unusually high rate of α-glycerophosphate oxidation was found both in cytoplasm and in mitochondria. The present finding strongly suggests that the α-glycerophosphate shuttle system operates actively in human term placenta. 2. The present studies revealed that cytoplasmic NAD-linked α-glycerophosphate dehydrogenase has only one molecular form. 3. The optimal temperature of cytosolic NAD-linked enzyme is about 55°. 4. The optimal pH for cytoplasmic NAD-linked enzyme is about 9.0. 5. The apparent Km of cytosolic NAD-linked α-glycerophosphate dehydrogenase at pH 10.0 is 3.9 mM for glycerophosphate and 1.05 mM for NAD^+.