It is proposed to continue an investigation of the structure, function, and mechanism of action of pig kidney general acyl-CoA dehydrogenase. Screening of group specific protein modification reagents will continue to attempt to identify amino acid side chains within the enzyme active center which are essential for enzymatic activity. Iodoacetic acid modifies a single essential methionine residue in the pig kidney enzyme, and investigation of this inactive carboxymethylated derivative will continue. The peptide bearing this reactive methionine residue will be isolated and its composition determined. Binding of various acyl-CoA derivatives to the flavoprotein will be studied to investigate those interactions which are important for effective catalysis. Efforts will continue to utilize active site directed and suicide substrates in the exploration of the mode of substrate dehydrogenation.