Kinetic mechanism of bovine liver argininosuccinate lyase.

The kinetic mechanism of bovine liver argininosuccinate lyase has been determined at pH 7.5, 25 degrees C. Fumarate and arginine are both noncompetitive inhibitors versus argininosuccinate. The dead-end inhibitor, succinate, is competitive versus fumarate and argininosuccinate, but noncompetitive versus arginine. Citrulline is competitive versus arginine and noncompetitive versus argininosuccinate and fumarate. The results are consistent with a random mechanism with the formation of two dead-end complexes: E . argininosuccinate . fumarate and E . argininosuccinate . arginine. No evidence was obtained for nonlinear reciprocal plots. The equilibrium constant was found to be 3.7 mM.