Employing peptide aldehyde inhibitors, model substrates, and the oxidized B chain of insulin the roles of three identified proteolytic acitve sites in the 20s and 26s proteosomes will be determined. Heterotropic and homotropic interactions between various types of catalytic sites will be examined. The sequence and tertiary structure dependence of the active sites will be examined. Isotope labeling studies will be employed to assess the role of processive processing in protein degradation by the proteasome will be explored. %%% The controlled degradation of proteins is just as important as their synthesis in the overall economy of the cell. Large and complex structures, the proteasomes, exist to degrade proteins and peptides. Such degradation plays roles in the immune system as well as in metabolism. The proposed research is designed to understand the mechanics of the protein degradation process and how it is controlled. The shear size of the proteasome and the complexity of its organization make this a problem of great difficulty, requiring the use of specific inhibitors to probe the various degradation active sites and the use of carefully designed protein and peptide substrates to examine the catalytic process.//
