title: Studies on enzyme models and on the enzyme carboxypeptidase A.
abstract: The enzyme carboxypeptidase A has been extensively studied and is thus a good candiate for chemical models and imitation. A model system was constructec which combined two of the three catalytic functional groups of the enzyme together with the appropriate substrate group, and cooperative effective catalysis was demonstrated. However, the mechanism which the model system used in enzyme-like conditions was unexpected, and this led to a study of the enzyme itself. Carboxypeptidase A was studied by examination of oxygen-18 exchange reactions and the ability of the enzyme to substitute only lytic agents, such as methanol, forthe water which is normally used. The result of these studies is proposed mechanism of action of this enzyme which accommodates the large amount of information already available, and which indicates that this enzyme uses a mechanism similar to that found in the model system. Approaches have also been made to an artificial enzyme which could hydrolyse amides. Cyclodextrin has been functionalized with two imidazole groups placed on opposite sides of the cavity. This material catalyses the hydrolysis of an amide, which binds to the cyclodextrin cavity and then is hydrolysed with the assistance of one imidazole in its basic form and the other one in its protonated form, acting together in a way reminiscent of the cooperation of some of the functional groups of hydrolytic enzymes.
mesh_terms: D001665:Binding Sites; D002268:Carboxypeptidases / Q000378:metabolism*; D008956:Models, Chemical; D010103:Oxygen Isotopes
chemical_list: D010103:Oxygen Isotopes; D002268:Carboxypeptidases