A FRAGMENT CONSISTING OF THE FIRST 204 AMINO-TERMINAL AMINO-ACIDS OF HUMAN ARYLAMINE N-ACETYLTRANSFERASE ONE (NAT1) AND THE FIRST TRANSACETYLATION STEP OF CATALYSIS

Human arylamine N-acetyltransferase 1 (NAT1) has 290 amino acids and a cetylates arylamines from acetyl coenzyme A. The acetyl group forms a thiolester with Cys 68 in the enzyme, and the acetyl group is then tra nsferred to the arylamine. When NAT1 is expressed using the pGEX vecto r, the glutathione S-transferase (GST)-NAT1 fusion protein catalyses t he acetylation of the NAT1 substrate e-aminobenzoic acid from acetyl C oA. Neither GST alone, nor a fusion protein of GST with the N-terminal 204 amino acids of NAT, catalyses the acetylation of p-aminobenzoic a cid from acetyl CoA. Using [H-3]acetyl CoA as substrate, it is shown t hat the full-length NAT1 and the N-terminal 204 amino acids of NAT1 ea ch form an acetylated intermediate on reaction with acetyl CoA. Copyri ght (C) 1996 Elsevier Science Inc.