AMP-AMINOHYDROLASE IN MUSCLE OF ELASMOBRANCH FISH . PURIFICATION PROCEDURE AND PROPERTIES OF PURIFIED ENZYME

1. 1. The procedure resulting in about 480-fold purification of AMP-aminohydrolase from white skeletal muscle of the elasmobranch fish Raia clavata is described. The procedure involves extraction with phosphate buffer, heat treatment, (NH4)2SO4 fractionation, adsorption on calcium phosphate gel and chromatography on DEAE-cellulose. 2. 2. The separation of AMP-aminohydrolase from actomyosin in fish muscle extracts was studied. 3. 3. The properties of the AMP-aminohydrolase purified from white skeletal muscle of the elasmobranch fish Raia clavata were investigated. 4. 4. The purified enzyme does not possess adenosine triphosphatase activity and is specific for 5′-AMP. The optimum pH was found to be 6·6 and the Michaelis-Menten constant in 0·1 M K-succinate buffer at 30°C was 1.sd52± 0·66×10-3 M. 5. 5. The allosteric activation of the enzyme by ATP and K+ was studied. The enzyme is also activated by 2′-AMP. The competitive inhibition of the enzyme by 3′-AMP was observed; Ki for 3′-AMP was found to be 3 × 10-3 M. 6. 6. The enzyme was inhibited by fluoride, inorganic phosphate and p-chloromercuribenzene sulphonic acid. 7. 7. The properties of fish muscle AMP-aminohydrolase are compared with those already known for mammalian enzyme. © 1969.