Properties and androgen-induced changes of arginase in kidney and ventral prostate of rats.

Abstract

Arginase activity in the kidney and the prostate of rats was found in both supernatant and precipitate after centrifugation at 12, 000×g for 20min. Ratios of enzyme activity in supernatant to precipitate varied in tissues examined; ratios of the liver and the ventral prostate were 5.5 and 2.3, respectively, however that of the kidney was 0.3. Arginase in the precipitate seems to be attached to membraneous element, because the activities of arginase are lost from nucleus after Triton X-100 treatment or heavy sucrose purification.Arginases from supernatant and precipitate in kidney and ventral prostate showed similar Km for substrate, but the rate of activation by Mn++ was slightly higher in supernatant than in precipitate.Castration caused a marked decrease of arginase activity in the precipitate of ventral prostate, while the change of the activity in supernatant was quite moderate. On the other hand, no significant changes of enzyme activity were observed in both supernatant and precipitate of the kidney. Testosterone treatment on castrated rats evoked an increase of the enzyme activity in the precipitate of kidney and of ventral prostate, and the elevation of the arginase activity in the supernatant was followed by the increase of the activity in the precipitate. The increase in the enzyme activity of ventral prostate was more prompt than in kidney after testosterone administration.