Acid and alkaline phosphatases in their relation to malignant disease.

Acid and Alkaline Phosphatases There are probably many different phosphatases present in living organisms and much valuable data is being accumulated on their identity and methods of differential estimation. In the present state of our knowledge, however, and from the aspect of clinical application, we can best think of them in terms of two groups, the socalled' alkaline ' and' acid' phosphatases. These enzymes are distinguished by the fact that the first class are optimally active at an alkaline and the second at an acid pH. The actual pH varies with the particular substrate, but when phenyl phosphate is used, the acid phosphatases have an optimum pH of 4.9 and the alkaline phosphatases are optimally active at pH 9.8. Since these pH values are sufficiently far apart, it is possible to determine one of the two groups of phosphatase in the presence of the other. It will be convenient in the first place to consider the two groups of phosphatases separately.