Kinetics of acetyl coenzyme A: Arylamine N-acetyltransferase from human cumulus cells

Purpose: N-acetyltransferase (NAT) activity is involved in the detoxificati on of exogenous amines. We aimed to evaluate the kinetics of acetyl coenzym e A (AcCoA): arylamine NAT for human cumulus cells. Methods. Thirty in fertile women who were undergoing controlled ovarian hyp erstimulation (COH) and oocyte retrievals were recruited Human cumulus cell s were obtained during oocyte retrievals. Using 2-aminofluorene (2-AF) and p-aminobenzoicacid (PABA) as substrates, NAT activity and Michaelis-Menten kinetics constants of all samples were determined by using high-pressure li quid chromatography. Results. There were 6 rapid, 10 intermediate, and 14 slow acetylators. 2-AF -NAT and PABA-NAT activities were 0.97 +/- 0.74 and 0.89 +/- 0.77 nmol/min/ mg protein, respectively. Km/V-max of rapid and slow acetylators for 2-AF w ere (161 +/- 55)/(15.6 +/- 2.9) and (27.8 +/- 11.4)/(2.6 +/- 0.9), respecti vely. Km/V-max of rapid and slow acetylators for PABA were (104 +/- 36)/(13 .2 +/- 2.8) versus (20.0 +/- 10)/(2.0 +/- 0.7), respectively Compared to sl ow acetylators, the rapid acetylators exhibited higher Km/V-max values for 2-A F (5.8-/6-fold) and PABA (6-/6.6-fold), respectively. Conclusion. Human cumulus could acetylate arylamine carcinogen (2-AF) and n oncarcinogen drug (PABA). Higher percentage of rapid acetylators establishe d in the cumulus during COH. It provides a model for monitoring the effects of pollution or carcinogenesis upon the oocyte during COH and oocyte retri evals.