Variation in the catalytic potential of AMP deaminase during muscular fatigue.

Substrate- and co-factor-dependent kinetics of AMP deaminase were studied in normal and fatigued gastrocnemius muscles of frog. Normal muscle enzyme showed greater enzyme co-factor affinity than enzyme-substrate affinity as evinced by low Kp values. Fatigue phenomenon was found to decrease the catalytic efficiency of the enzyme by lowering the enzyme-substrate affinity more than the enzyme-co-factor affinity and enhancing activation energy values. Present study elucidates the low level of operation of adenine nucleotide deamination involving AMP-deaminase reacting-system during prolonged contractile stress.