Homology modeling and prediction of the amino acid residues participating in the transfer of acetyl-CoA to arylalkylamine by the N-acetyltransferase from Chryseobacterium sp.

ABSTRACT

OBJECTIVES: To predict the amino acid residues playing important roles in acetyl-CoA and substrate binding and to study the acetyl group transfer mechanism of Chryseobacterium sp. 5-3B N-acetyltransferase (5-3B NatA). RESULTS: A 3-dimensional homology model of 5-3B NatA was constructed to compare the theoretical structure of this compound with the structures of previously reported proteins belonging to the bacterial GCN5 N-acetyltransferase family. Homology modeling of the 5-3B NatA structure and a characterization of the enzyme's kinetic parameters identified the essential amino acid residues involved in binding and acetyl-group transfer. 126Leu, 132Leu, and 135Lys were implicated in the binding of phosphopantothenic acid, and 100Tyr and 131Lys in that of adenosyl biphosphate. The data supported the participation of 83Glu and 133Tyr in catalyzing acetyl-group transfer to L-2-phenylglycine. CONCLUSIONS: 5-3B NatA catalyzes the enantioselective N-acetylation of L-2-phenylglycine via a ternary complex comprising the enzyme, acetyl-CoA, and the substrate.