Histochemical and biochemical studies of the kinetics of non-specific acid phosphatase in rat kidney.

Kinetic characteristics of non-specific acid phosphatase (orthophosphoric monoester phosphohydrolase, E.C.3.1.3.2.) from rat kidney were determined fluorometrically using 4-methylumbelliferyl phosphate as the substrate. Kinetic characteristics measured by similar methods both histochemically in cryostat sections and biochemically in tissue extracts were compared. Histochemical and biochemical methods gave essentially similar results in respect of Michaelis-Menten constants (Km), pH optima, effect of fluoride inhibition and the effect of changes in incubation temperatures in the range 10 degrees C to 37 degrees C. This confirms the validity of both methods, and also gives greater confidence that the enzyme in vitro closely approximates the properties of the enzyme as it functions in vivo.