Investigattons will continue on metabolic pathways concerned in the bioconversion of aromatic acids to their peptide conjugates. Specifically, indoleacetyl-CoA and phenylacetyl-CoA will be characterized chemically and by ultraviolet and NMR spectroscopy. The substrate and inhibition specificity of mitochondrial acyl-CoA: amino acid N-acyltransferases from beef and rhesus monkey liver will also be determined. Further studies will be carried out on the number o subunits and binding sites of acetyl-CoA synthetase from ox heart mitochondria.