Activities | Families | Sequences | Fold types | References | Help
B6db references: 12137566

type Journal Article
authors Cooper, A. J.; Bruschi, S. A.; Iriarte, A.; Martinez-Carrion, M.
title Mitochondrial aspartate aminotransferase catalyses cysteine S-conjugate beta-lyase reactions
journal Biochem J
sel selected
ui 12137566
year (2002)
volume 368
number Pt 1
pages 253-261
abstract Rat liver mitochondrial aspartate aminotransferase (a homodimer) was shown to catalyse a beta-lyase reaction with three nephrotoxic halogenated cysteine S-conjugates [ S -(1,1,2,2-tetrafluoroethyl)-L- cysteine, S -(1,2-dichlorovinyl)-L-cysteine and S -(2-chloro-1,1,2- trifluoroethyl)-L-cysteine], and less effectively so with a non-toxic cysteine S-conjugate [benzothiazolyl-L-cysteine]. Transamination competes with the beta-lyase reaction, but is not favourable. The ratio of beta elimination to transamination in the presence of S -(1,1,2,2- tetrafluoroethyl)-L-cysteine and 2-oxoglutarate is >100. Syncatalytic inactivation by the halogenated cysteine S-conjugates is also observed. The enzyme turns over approx. 2700 molecules of halogenated cysteine S- conjugate on average for every monomer inactivated. Kidney mitochondria are known to be especially sensitive to toxic halogenated cysteine S- conjugates. Evidence is presented that 15-20% of the cysteine S- conjugate beta-lyase activity towards S -(1,1,2,2-tetrafluoroethyl)-L- cysteine in crude kidney mitochondrial homogenates is due to mitochondrial aspartate aminotransferase. The possible involvement of mitochondrial aspartate aminotransferase in the toxicity of halogenated cysteine S-conjugates is also discussed.
last changed 2009/07/01 14:12

B6db references