This represents the thesis work dedicated to unraveling the underlying catalytic mechanism of the exopeptidase carboxypeptidase A. Earlier postulated mechanisms (by Cleland et.al., Lipscomb et.al., Suh et. al…), based on crystallographic and kinetic data, are experimentally and theoretically critically explored. Various synthetic (novel and past) substrates were used and studied by applying advanced kinetics. The synthesis of a novel substrate with unprecedented kinetic features (extreme kcat/Km value) assured excellent compatibility with the transition state structure of the enzyme; permitting the exclusion of several earlier proposed mechanisms. Multi- inhibitor analysis maps the likely location of substrates within this multi-subsite enzyme in the active catalytic state. Further, the study demonstrates a very early case of multi-subsite cooperative interaction in a monomeric enzyme. Later studies have substantiated this important aspect in other enzymes (FE: RNase A, 1999; phospholipase, 2001). It is currently believed that this is a common property of several enzymes and proteins that act on biopolymers and membrane lipids.