睾丸腫瘍患者血清にみられた異常高値LDH-I(B4) の性状

抄録

A case with testicular carcinoma (S.G., 22 years old man, Clinical diagnosis: Embryonal carcinoma), total serum LDH activity being 7 times higher than that of normal upper range, was reported. Using a fractional analysis of the serum LDH, it was demonstrated that LDH-I fraction which assumed to be derived from the tumor tissue was significantly elevated (maximum about 90%). In the next step, biochemical properties of this serum LDH was investigated. As to attitudes against various inhibitors, Michaelis constant(Km), optimum pH and thermostabilities in 37, 65°C, this LDH was identical with normal LDH or LDH in a patient with myocardial infarction. This LDH, however, activated rather than maintained its enzymatic activity for about 80 minutes in 56°C, demonstrating a stronger than thermal stability of standard LDH of myocardial type.