STUDIES ON PHENOL FORMATION

III. AMMONIUM AND POTASSIUM IONS AS THE ACTIVATOR OF BETA-TYROSINASE

Abstract

1. Phenol, pyruvate and NH₃ are produced from tyrosine by the β-tyrosinase, obtained from B. coli phenologenes, in an equimolar ratio simultaneously.
2. Pyridoxal phosphate is the coenzyme of the β-tyrosinase.
3. For this reaction, the presence of NH₄⁺ or K⁺ is required and Na⁺ or Li⁺ counteract K⁺ or NH₄⁺ activation. The previous report was thus corrected.
4. This enzyme is inhibited by metal chelating compounds. Therefore, the participation of a certain heavy metal is suggested.
5. This enzyme is also inhibited by various SH reagents, and regains its activity by the addition of mercapto compounds. Concequently the participation of the SH group is suggested.
6. The mechanism of the enzymatic reaction is discussed.