title: Differential redox potential between the human cytosolic and mitochondrial branched-chain aminotransferase.
abstract: The human branched-chain aminotransferase (hBCAT) isoenzymes are CXXC motif redox sensitive homodimers central to glutamate metabolism in the central nervous system. These proteins respond differently to oxidation by H(2)O(2), NO, and S-glutathionylation, suggesting that the redox potential is distinct between isoenzymes. Using various reduced to oxidized glutathione ratios (GSH:GSSG) to alter the redox environment, we demonstrate that hBCATc (cytosolic) has an overall redox potential that is 30 mV lower than hBCATm (mitochondrial). Furthermore, the CXXC motif of hBCATc was estimated to be 80 mV lower, suggesting that hBCATm is more oxidizing in nature. Western blot analysis revealed close correlations between hBCAT S-glutathionylation and the redox status of the assay environment, offering the hBCAT isoenzymes as novel biomarkers for cytosolic and mitochondrial oxidative stress.
authors: Department of Medical Genetics, Haematology and Pathology, School of Medicine, Cardiff University, South Wales, UK.
authors: Steven J
authors: SJ
authors: Coles
authors: John T
authors: JT
authors: Hancock
authors: Myra E
authors: ME
authors: Conway
mesh_terms: D020816:Amino Acid Motifs; D003600:Cytosol / Q000201:enzymology; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D015778:Minor Histocompatibility Antigens; D008928:Mitochondria / Q000201:enzymology; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011257:Pregnancy Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000637:Transaminases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D015778:Minor Histocompatibility Antigens; D011257:Pregnancy Proteins; D011994:Recombinant Proteins; C490590:BCAT1 protein, human; D000637:Transaminases; C424463:BCAT2 protein, human; D005978:Glutathione; D019803:Glutathione Disulfide