抄録
Arginase (E. c. 3. 5. 3. 1., L-arginine ureohydrolase) in the liver of ureoteric animals plays an important role as a member of urea cycle enzyme system. However, the physiological role of the extrahepatic arginase is unclear. Arginase in rat prostate was reported to be under hormonal control. In this paper, we confirmed the activity of arginase in human prostatic tumors and investigated some properties of this enzyme. The following results were obtained :
1) The high enzyme activity was observed in benign prostatic hypertrophy and adenocarcinoma of prostate. In benign prostatic hypertrophy, tissues exhibiting the adenomatous type had higher activity than tissues exhibiting fibromuscular type. In prostatic cancer, the enzyme activity in undifferentiated adenocarcinoma was lower than that in well-differentiated ones, and treatment of the latter with estrogen decreased the enzyme activity.
2) The rate of Mn++ activation in the 12, 000 g supernatant of benign prostatic hypertrophy was remarkably high, as compared with prostatic cancer. It was suggested that zinc might be concerned with this phenomen.
3) Free zinc had an inhibitory action on arginase activity of 12, 000 g supernatant of benign prostatic hypertrophy and this inactivation was prevented or reversed by manganeseion.
