Erythrocyte glutathione transferase: a general probe for chemical contaminations in mammals

Abstract

Glutathione transferases (GSTs) are enzymes devoted to the protection of cells against many different toxins. In erythrocytes, the isoenzyme (e-GST) mainly present is GSTP1-1, which is overexpressed in humans in case of increased blood toxicity, as it occurs in nephrophatic patients or in healthy subjects living in polluted areas. The present study explores the possibility that e-GST may be used as an innovative and highly sensitive biomarker of blood toxicity also for other mammals. All distinct e-GSTs from humans, Bos taurus (cow), Sus scrofa (pig), Capra hircus (goat), Equus caballus (horse), Equus asinus (donkey) and Ovis aries (sheep), show very similar amino acid sequences, identical kinetics and stability properties. Reference values for e-GST in all these mammals reared in controlled farms span from 3.5±0.2 U/gHb in the pig to 17.0±0.9 U/gHb in goat; such activity levels can easily be determined with high precision using only a few microliters of whole blood and a simple spectrophotometric assay. Possibly disturbing factors have been examined to avoid artifact determinations. This study provides the basis for future screening studies to verify if animals have been exposed to toxicologic insults. Preliminary data on cows reared in polluted areas show increased expression of e-GST, which parallels the results found for humans.

Erythrocyte glutathione transferase in kidney transplantation: a probe for kidney detoxification efficiency

“…The level of reduced HSA cannot be evaluated by direct titration of its reduced Cys34 by DTNB, because this thiol reagent reacts very slowly with this cysteine. We therefore used a modified procedure 50 based on the fast reaction of cystamine with Cys34. The released cysteamine is stoichiometric with Cys34 and easily determined with DTNB (ε 412 nm of TNB - : 14.1 mM -1 cm -1 ).…”

Thiol disulfide exchange reactions in human serum albumin: the apparent paradox of the redox transitions of Cys34

“…Cys 34 in the reduced albumin reacts with DTNB at very low velocity [13,35] so its quantification in a short time was performed taking advantage by the very fast reaction of Cys 34 with cystamine (Table 1) [36]. The released cysteamine (stoichiometric to Cys 34 ) can be titrated within two min with DTNB (see below).…”

Single nucleotide polymorphisms and microsatellites in the canine glutathione S-transferase pi 1 (GSTP1) gene promoter

“…GST pi 1 (GST-P1) is expressed in extrahepatic tissues such as placenta, lung, gut and erythrocytes [ 2 , 3 ], where it is involved in the biotransformation of carcinogens such as acrolein [ 4 ], and benzo[a]pyrene diol epoxide (BPDE) [ 5 ], endocrine-disrupting pesticides such as atrazine [ 6 ], and numerous drugs, including cisplatin [ 7 ] and chlorambucil [ 8 ]. While humans and rats express one subunit belonging to the P1 class of GSTs, GSTP1, mice express two pi subunits, GSTP1 and GSTP2.…”