Role of human sulfide: quinone oxidoreductase in H2S metabolism.
The first step in the mammalian metabolism of H2S is catalyzed by sulfide:quinone oxidoreductase (SQOR). Human SQOR is an integral membrane protein, which presumably interacts with the inner mitochondrial membrane in a monotopic fashion. The enzyme is a member of a family of flavoprotein disulfide oxidoreductases (e.g., glutathione reductase) that utilize a Cys-S-S-Cys disulfide bridge as an additional redox center. SQOR catalyzes a two-electron oxidation of H2S to sulfane sulfur using coenzyme Q as electron acceptor. The enzyme also requires a third substrate to act as the acceptor of the sulfane sulfur from a cysteine persulfide intermediate. Here, we describe a method for the bacterial expression of human SQOR as a catalytically active membrane-bound protein, procedures for solubilization and purification of the recombinant protein to >95% homogeneity, and spectrophotometric assays to monitor SQOR-mediated H2S oxidation in reactions with different sulfane sulfur acceptors.
Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, Pennsylvania, USA.
Michael R
MR
Jackson
Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, Pennsylvania, USA.
Scott L
SL
Melideo
Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, Pennsylvania, USA. Electronic address: marilyn.jorns@drexelmed.edu.
Marilyn Schuman
MS
Jorns
D055162:Biocatalysis; D057075:Enzyme Assays; D004926:Escherichia coli; D006801:Humans; D006862:Hydrogen Sulfide / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D010084:Oxidation-Reduction; D011808:Quinone Reductases / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*
D011808:Quinone Reductases; C073412:sulfide quinone reductase; D006862:Hydrogen Sulfide
Catalytic properties of human SQOR; Expression and purification of human SQOR; Role of human SQOR in mitochondrial H(2)S metabolism; Spectral properties and flavin content of human SQOR; Spectrophotometric assays of human SQOR; Sulfide: quinone oxidoreductase (SQOR)