Pyruvate dehydrogenase complex provides an important metabolic link betweenglycolysis nd the complete oxidation of glucose zit commits pyruvate tooxidation via acetyl-CoA and Krebs Cycle since there is no biochemicalmeans by which acetyl-CoA can be converted back to pyruvate. The activityof pyruvate dehydrogenase complex is controlled by reversiblephosphorylation. Evidence obtained just recently indicates that the systemresponsible for covalent modification of pyruvate dehydrogenase isorganized in a muchmore complex way than was believed before. It appearsthat mammalian pyruvate dehydrogenase kinase responsible forphosphorylation and inactivation of pyruvate dehydrogenase i belongs to anew family of eukaryotic serine-specific protein kinases, ii exists as twoisoenzymic forms different in terms of primary structure and tissuedistribution, and iii may be a subject of regulation by phosphorylation- dephosphorylation itself. The current proposal is designed to continue thestudies on the regulation of pyruvate dehydrogenase in directions thatfollow form these new data. It targets characterization of the catalyticmechanism of pyruvate dehydrogenase kinase, the determination of theregulatory properties of the two isoforms of the kinase, and theelucidation of the role of autophosphorylation of the first isoform ofpyruvate dehydrogenase kinase in regulation of its activity. The detailedspecific aims of this proposal are; 1 to identify the amino acid residueswithin the catalytic domain of pyruvate dehydrogenase kinase important forkinase function: 2 to characterize the regulatory properties of the twoisoforms of pyruvate dehydrogenase kinase; and 3 to characterize the roleof autophosphorylation of serine residues in the regulation of pyruvatedehydrogenase kinase activity. The accomplishment of these goals will notonly bring nre insight into our understanding of the structure and functionof pyruvate dehydrogenase complex, but will also allow investigators tomove further toward characterization of the molecular mechanismsresponsible for i selection respiratory fuels in mammals duringstarvation, ii tissue specific differences in regulation of aerobicoxidation of glucose, and iii abnormal regulation of pyruvatedehydrogenase complex in pathogenesis of diabetes, cancer, sepsis, cardiomyopathy and obesity.
Aldehyde Ketone Oxidoreductase, Cellular Respiration, Circular Dichroism, Enzyme Activity, Enzyme Mechanism, Enzyme Structure, Isozyme, Laboratory Rat, Mitochondria, Phosphorylation, Point Mutation, Protein Kinase, Protein Sequence, Protein Structure Function, Pyruvate Dehydrogenase