Date of Award

Fall 1976

Degree Type

Thesis - Restricted




In an attempt to resolve the conflicting reports about the effect of substrate binding on the conformation of carboxypeptidase (CPA) spin labeling technique has been used to determine the conformation of a functional group (Tyr 248) at the active site of the enzyme. The first task was to prepare a spin label to selectively label the tyrosine residue in the vicinity oi the active site. N-(2,2,5,5 tetramethyl- 3-carbonyl-pyrrolidine-l-oxyl)-imidazole (I) which is an analogue of tyrosine specific N-acetylimidazole has been prepared sucessfully and its usefulness for spin labeling other molecules of biological interest has, been investigated. CPA was spin labeled with (I) in the presence and absence of the competitive inhibitor (B-phenyl propionate). Kinetic assays and esr studies of the spin labeled enzyme were carried out and the results are reported.