KINETICS OF NICOTINAMIDE NUCLEOTIDE TRANSHYDROGENATION BY HUMAN PLACENTA.
1. Measurements of kinetic constants for a purified preparation of human-placenta oestradiol dehydrogenase have been made. 2. These constants have been compared with similar measurements made on crude ammonium sulphate precipitates of human-placenta homogenates. The comparison indicates that nearly half of the observed nicotinamide nucleotide-transhydrogenation activity in the crude preparations is due to a specific oestrogen-dependent transhydrogenase. 3. The remainder of the observed activity results from a substrate-mediated transhydrogenation catalysed by the oestradiol-dehydrogenase activities present in the preparation.
D001669:Biochemical Phenomena; D001671:Biochemistry; D002384:Catalysis; D004958:Estradiol; D004970:Estrone; D005260:Female; D006801:Humans; D007700:Kinetics; D009243:NAD; D009249:NADP; D009536:Niacinamide; D010084:Oxidation-Reduction; D010088:Oxidoreductases; D010920:Placenta; D011247:Pregnancy; D012106:Research; D013053:Spectrophotometry
D009243:NAD; D009536:Niacinamide; D004970:Estrone; D004958:Estradiol; D009249:NADP; D010088:Oxidoreductases
BIOCHEMISTRY; CATALYSIS; ESTRADIOL; ESTRONE; EXPERIMENTAL LAB STUDY; KINETICS; NAD; NADP; OXIDOREDUCTASES; PLACENTA; SPECTROPHOTOMETRY