心，肝疾患時の血清アスパラギン酸トランスアミナーゼ（AST）のミカエリスーメンテン定数

Michaelis-Menten Constant of Serum Aspartate Amino Transferase (AST) in Heart and Liver Disease

　正常人と最近心筋梗塞を起こした患者ならびに流行性肝炎の患者で，血清アスパラギン酸トランスアミナーゼ（AST）の活性とKm（ミカエリスーメンテン定数）が検討された．AST活性は両患者群で上昇していた．心筋梗塞では血清ASTのKm値は変化はなかったが，流行性肝炎で総血清ビリルビンが13mg/dlより高いときには増加した．このようなわけで，心，肝疾患の鑑別診断にはAST活性の研究は，役に立たなかったが，流行性肝炎の診断にはKm値の決定が有用であった．

The activity and the Km (Michaelis-Menten constant) of serum aspartate amino transferase (AST) were investigated in normal subjects, in patients with recent myocardial infarction, and in patients with infectious hepatitis. AST activity was elevated in both groups of patients. While the Km value of serum AST was not affected in myocardial infarction, it was increased in infectious hepatitis when the total serum bilirubin was higher than 13 mg/dl. Thus, while an investigation of activity of AST in serum did not help in differential diagnosis of heart and liver diseases, determination of Km value was helpful in the diagnosis of infectious hepatitis.