Date of Award

Spring 1975

Degree Type

Thesis - Restricted

Degree Name

Master of Science (MS)




The enzymatic activity of the pyruvate dehydrogenase complex (PDC) and one of its enzymatic components, dihydrolipoamide transacetylase (LTA), has been examined in mitochondrial extracts of Neurospora crassa grown on either acetate or glucose as the sole carbon source. The specific activity of the complex, as measured in the overall reaction of pyruvate to acetyl-CoA, is significantly reduced in acetate grown cells, although there is approximately a two-fold increase in the specific activity of LTA. The possibility that the higher enzymatic activities of LTA in mitochondrial extracts are the result of a separate enzymatic moiety not identical to the PDC appears to be excluded by the finding that the LTA has a mitochondrial location and physical properties identical to that of the PDC. Transfer of acetate grown cultures to glucose media leads to an increase in the specific activity of PDC, but this increase is growth dependent, requiring approximately four mass doublings to attain fully induced enzyme levels. These data suggest that changes in PDC activity are the result of an associated cofactor or protein component synthesized in response to a specific metabolic effector.