The detailed mechanisms of serine hydroxymethylase, galactose-1 phosphate uridylyl transferase and beta-lactamases (penicillinases) will be determined by pre-steady state, steady state, and relaxation kinetic analyses in the presence of various concentrations of substrates, products, and inhibitors. From the pH dependencies of the elementary steps in the kinetic sequences, isolation of possible covalent enzyme-substrate moiety intermediates, active site directed reagents, isotopic exchange reactions and kinetic isotope effects, etc. in conjunction with primary sequence and, in at least one instance, X-ray diffraction data, correlations between the kinetic processes and the structures of the enzyme active sites will be made. These correlations will be compared with data obtained in relevant model system studies to elucidate the contributions to catalysis in the enzyme catalyzed sequences. The mechanistic studies of model reactions will include investigations of the pyridoxal-5'-phosphate catalyzed dealdolization of substituted beta-phenylserines, the ligation and carbon-cobalt cleavage reactions of alkylcobaloximes, the reactions of amino acids (histidine, lysine, arginine, tryptophan, and tyrosine) with carbonyl compounds (formaldehyde) to form cyclic products, and the Mannich reaction.