Identity of rat kidney and urine alkaline phosphatase actions and relation to the effect of nitrofuranfuradroxyl.

The activities of alkaline phosphatases of kidney and urine appear similar and identical in action. Both are magnesium-dependent and inhibited by higher concentrations of 2-glycerophosphate. A band of similar mobility is obtained on electrophoresis of kidney and urine enzymes. In vitro magnesium competitively inhibits their activities when the ratio of Mg-+2 ions/2-glycerophosphate is above a definite level. Their activities are not affected by exogenous zinc and follow the Michaelis-Menten equation only when attention is given to the ratio of Mg-+2 ions/substrate. Nitrofuranfuradroxyl is a mixed type inhibitor showing a second-order rate of reaction with kidney and urine phosphatases.