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

Abstract

Purpose: N-acetyltransferase (NAT) activity is involved in the detoxification of exogenous amines. We aimed to evaluate the kinetics of acetyl coenzyme A (AcCoA): arylamine NAT for human cumulus cells. Methods: Thirty infertile women who were undergoing controlled ovarian hyperstimulation (COH) and oocyte retrievals were recruited. Human cumulus cells were obtained during oocyte retrievals. Using 2-aminofluorene (2-AF) and p-aminobenzoic acid (PABA) as substrates, NAT activity and Michaelis-Menten kinetics constants of all samples were determined by using high-pressure liquid 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/Vmax of rapid and slow acetylators for 2-AP were (161±55)/(15.6±2.9) and (27.8±11.4)/(2.6±0.9), respectively. Km/Vmax 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 slow acetylators, the rapid acetylators exhibited higher Km/Vmax values for 2-AF (5.8-/6-fold) and PABA (6-/6.6-fold), respectively. Conclusion: Human cumulus could acetylate arylamine carcinogen (2-AF) and noncarcinogen drug (PABA). Higher percentage of rapid acetylators established in the cumulus during COH. It provides a model for monitoring the effects of pollution or carcinogenesis upon the oocyte during COH and oocyte retrievals.