反芻動物の蛋白質消化に関する研究-8-牛第一胃粘膜のグルタミック-ピルビックトランスアミナーゼについて〔英文〕

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Transaminase activity in the bovine rumen mucosa was studied. Glutamic-pyruvic transaminase activity per wet weight of tissues was higher in the rumen mucosa than in the heart. When the activity was estimated by per mg protein of tissues, the rumen papillary was more active than the liver. Glutamic-pyruvic transaminase was purified 30-fold from rumen mucosa extracts and enzymatic properties of it was studied. The enzyme activity was linear for the first 60min, and proportinal to the protein concentration of the enzyme preparation. The optimum temperature was 60°C, and even at 70°C much of the activity was retained for one hour. The optimum pH was 8.0 in phosphate buffer. It was shown that p-chloromercuribenzoate and HgCl2 were potent inhibitors, whereas monoidoacetic acid had no effect on the enzyme activity. Glutathione reversed completely the inhibition by p-chloromercuribenzoate. The enzyme required pyridoxal phosphate as a cofactor.Rumen mucosa extracts catalized reactions which transaminated some amino acids with α-ketoglutaric acid to form glutamic acid. Amino acids which were available as amino donors were alanine, aspartic acid, isoleucine, leucine, methionine, phenylalanine and valine.
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