STEREOSELECTIVE CATALYSIS OF A RETRO-MICHAEL REACTION BY CLASS-MU GLUTATHIONE TRANSFERASES - CONSEQUENCES FOR THE INTERNAL DISTRIBUTION OF PRODUCTS IN THE ACTIVE-SITE

被引：27

作者：

CHEN, JH ^{[1
]}

ARMSTRONG, RN ^{[1
]}

机构：

[1] UNIV MARYLAND,DEPT CHEM & BIOCHEM,COLLEGE PK,MD 20742

来源：

CHEMICAL RESEARCH IN TOXICOLOGY | 1995年 / 8卷 / 04期

关键词：

D O I：

10.1021/tx00046a012

中图分类号：

R914 [药物化学];

学科分类号：

100701 ;

摘要：

The reaction of glutathione (GSH) with trans-4-phenyl-3-buten-2-one (PBO) is readily reversible in aqueous solution with an apparent (pH-dependent) equilibrium constant at pH 8 of 6.4 x 10(2) M(-1). Two class mu isoenzymes of GSH transferase from rat (M1-1 and M2-2) and two site specific mutants (M1-1/V9I and M2-2/I9V) catalyze the addition of GSH to PBO and the elimination of GSH from the two diastereomeric products (isomers A and B) of 4-(S-glutathionyl)-4-phenyl-2-butanone with varying degrees of efficiency and stereoselectivity, with the major kinetic product in the addition reaction (isomer A) being the preferred substrate for the elimination reaction. The kinetic stereoselectivity of the addition reaction and the steady-state kinetics of the elimination reactions with product isomers A and B are used to estimate internal stereochemical equilibrium constants in which product isomer B is predominant. This result is consistent with the internal equilibrium constants measured under conditions of enzyme in excess. The results can be used to construct reaction coordinate diagrams for the interconversion of central complexes in the enzyme-catalyzed reactions. The possible metabolic consequences of the reversibility of additions of GSH to alpha,beta-unsaturated carbonyl compounds are discussed.

引用

页码：580 / 585

页数：6

共 21 条

[1] Alin P., Danielson U.H., Mannervik B., 4-Hydroxy-alk-2-enals are substrates for glutathione transferase, FEBS Lett., 179, pp. 267-270, (1985)
[2] Danielson U.H., Esterbauer H., Mannervik B., Structure-activity relationships of 4-hydroxyalkenals in the conjugation catalyzed by mammalian glutathione transferases, Biochem J., 247, pp. 707-713, (1987)
[3] Berhane K., Widersten M., Engstrom A., Kozarich J.W., Mannervik B., Detoxication of base propenals and other α,β-unsaturated aldehyde products of radical reactions and lipid peroxidation by human glutathione transferases, Proc. Natl. Acad. Sci. U.S.A., 91, pp. 1480-1484, (1994)
[4] Beauchamp R.O., Andjelkovich D.A., Kligerman A.D., Morgan K.T., Heck H.D., A critical review of the literature on acrolein toxicity, CRC Crit Rev. Toxicol., 14, pp. 309-380, (1985)
[5] Morgenstern R., DePierre J.W., Lind C., Guthenberg C., Mannervik B., Ernster L., Benzo(a)pyrene quinones can be generated by lipid peroxidation and are conjugated with glutathione by glutathione S-transferase B from rat liver, Biochem. Biophys. Res. Commun., 99, pp. 682-690, (1981)
[6] Ploemen J.H.T.M., van Ommen B., van Bladeren P.J., Inhibition of rat and human glutathione S-transferase isoenzymes by ethacrynic acid and its glutathione conjugate, Biochem. Pharmacol., 40, pp. 1631-1635, (1990)
[7] Baillie T.A., Slatter J.G., Glutathione
[8] A vehicle for the transport of chemically reactive metabolites in vivo, Acc. Chem. Res., 24, pp. 264-270, (1991)
[9] Monks T.J., Anders M.W., Dekant W., Stevens J.L., Lau S.S., van Bladeren P.J., Glutathione conjugate mediated toxicities, Toxicol. Appl. Pharmacol., 106, pp. 1-19, (1990)
[10] Habig W.H., Pabst M.J., Jakoby W.B., Glutathione S-transferases. The first enzymatic step in mercapturic acid formation, J. Biol. Chem., 249, pp. 7130-7139, (1974)

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