THE pH STABILITY OF PROTYROSINASE AND TYROSINASE.

1. pH stability diagrams for protyrosinase and for tyrosinase were constructed. 2. Above pH 7.30 protyrosinase is unstable. Between pH 7.30 and pH 9.30 there is a partial destruction. Beyond pH 9.30 it changes irreversibly into tyrosinase which in turn is destroyed beyond pH 10.12. 3. Through the lower ranges of pH protyrosinase is less stable than tyrosinase The former is destroyed below pH 4.80, while the latter is unaffected until the pH drops below 4.10. 4. The tyrosinase produced at high pH values resembles that produced by other methods.