Myosin as Adenlylic Acid Deaminase

Extraction and Some Properties of Adenosine 5′-Monophosphate Aminohydrolase from Prerigor and Postrigor Muscle of Cod

Adenosine 5′-monophosphate aminohydrolase (EC 3.5.4.6) activity of prerigor cod muscle could be extracted with water or 0.02 M succinate buffer in about 90% yield, but 0.02 M KCl gave a low yield. With postrigor muscle, the enzyme tended to be associated with the fibrillar protein fractions. The activity of the unpurified enzyme, measured by a pH-stat, showed a maximum at pH 7.0 in 0.02 M succinate, and about pH 6.6 in 0.1 M KCl. At pH 7.0, activities were maximal and approximately equal in 0.1 M KCl, 0.1 M NaCl, and 0.04 M potassium succinate. Phosphate buffer inhibited the reaction under certain conditions. The enzyme was sensitive to glass and other surfaces, and this seemed to be responsible for loss of activity during dialysis. The activation energy was 10 kcal per mole and the Michaelis–Menten constant was 1.4 × 10−3 moles per litre.