REGULATORY PROPERTIES OF AMP-DEAMINASE FROM SNAPPER MUSCLE

The influence of various nucleotides on the activity of AMP deaminase (EC 3.5.4.6) from skeletal muscle of snapper Pagrus auratus has been i nvestigated. The enzyme was activated by 1 mM adenine nucleotides such as ATP and ADP. The substrate-saturation curve of the enzyme was sigm oidal in the absence of effectors, but it changed to a hyperbolic curv e through the addition of ATP, ADP, and K+. ATP proved to have a bipha sic effect on the enzyme, in other words the enzyme was inhibited by A TP at a low concentration of 0.1 mM and activated at a higher concentr ation. The enzyme activity was inhibited effectively by GTP ranging fr om 0.1 to 5 mM at a substrate concentration of 1 mM AMP, and the inhib itory ratio showed a maximum value of 67% by the addition of 0.1 mM GT P in the absence of K+, while 50 mM KCl can essentially reverse the in hibition of the enzyme activity by GTP.The regulatory property of snap per muscle AMP deaminase activated by ATP is similar to those of the e nzymes from the internal organs of animals, the muscle of other fishes , and baker's yeast.