title: Redox regulation and trapping sulfenic acid in the peroxide-sensitive human mitochondrial branched chain aminotransferase.
abstract: The human branched chain aminotransferase enzymes are key regulators of glutamate metabolism in the brain and are among a growing number of redox-sensitive proteins. Studies that use thiol-specific reagents and electrospray ionization mass spectrometry demonstrate that the mitochondrial BCAT enzyme has a redox-active CXXC center, which on oxidation forms a disulfide bond (RSSR), via a cysteine sulfenic acid intermediate. Mechanistic details of this redox regulation were revealed by the use of mass spectrometry and dimedone modification. We discovered that the thiol group at position C315 of the CXXC motif acts a redox sensor, whereas the thiol group at position C318 permits reversible regulation by forming an intrasubunit disulphide bond. Because of their roles in redox regulation and catalysis, there is a growing interest in cysteine sulphenic acids. Therefore, development of chemical tags/methods to trap these transient intermediates is of immense importance.
authors.affiliation: Wake Forest University Health Sciences, Winston-Salem, NC, USA.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Hutson
authors.forename: Leslie B
authors.initials: LB
authors.lastname: Poole
authors.forename: Steven
authors.initials: S
authors.lastname: Coles
authors.forename: Myra E
authors.initials: ME
authors.lastname: Conway
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001681:Biological Assay; D020134:Catalytic Domain; D003512:Cyclohexanones / Q000737:chemistry; D004228:Dithionitrobenzoic Acid; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D013058:Mass Spectrometry; D008928:Mitochondria / Q000187:drug effects* / Q000201:enzymology*; D008967:Molecular Biology / Q000379:methods*; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000302:isolation & purification; D010084:Oxidation-Reduction / Q000187:drug effects; D013053:Spectrophotometry; D013434:Sulfenic Acids / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000032:analysis; D000637:Transaminases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D003512:Cyclohexanones; D050505:Mutant Proteins; D013434:Sulfenic Acids; D013438:Sulfhydryl Compounds; D004228:Dithionitrobenzoic Acid; C004774:dimedone; D006861:Hydrogen Peroxide; D000637:Transaminases; C019798:branched-chain-amino-acid transaminase