Conjugation of 4-hydroxynonenal by largemouth bass (Micropterus salmoides) glutathione S-transferases

Abstract

The glutathione S-transferases (GST) are a major group of conjugative enzymes involved in the detoxification of electrophilic compounds and products of oxidative stress. We have previously described the kinetics of hepatic GST conjugation in largemouth bass using a variety of synthetic GST reference substrates. In the present study, we investigated the ability of largemouth bass hepatic GSTs to conjugate 4-hydroxynon-2-enal (4HNE), a mutagenic and cytotoxic α-β-unsaturated aldehyde produced during oxidative injury. Hepatic cytosolic fractions from largemouth bass rapidly catalyzed GSH-dependent 4HNE conjugation, with the rate of GST-4HNE conjugation in bass liver exceeding those of several other mammalian and aquatic species. No apparent sex-related differences in GST-4HNE activity were observed among adult bass. SDS-PAGE and Western blotting analysis of GSH affinity-purified bass liver cytosolic GST revealed the presence of two major GST subunits of approximately 30 and 27 KDa that exhibited slight cross-reactivity when probed with a rat alpha class GST antibody, but not to rat mu, pi or theta class GST. The rapid conjugation of 4HNE by hepatic GST suggests an important role for GSTs in protecting against peroxidation of polyunsaturated fatty acids in bass liver.