Hydrogen Sulfide Oxidation by Myoglobin.
Enzymes in the sulfur network generate the signaling molecule, hydrogen sulfide (H2S), from the amino acids cysteine and homocysteine. Since it is toxic at elevated concentrations, cells are equipped to clear H2S. A canonical sulfide oxidation pathway operates in mitochondria, converting H2S to thiosulfate and sulfate. We have recently discovered the ability of ferric hemoglobin to oxidize sulfide to thiosulfate and iron-bound hydropolysulfides. In this study, we report that myoglobin exhibits a similar capacity for sulfide oxidation. We have trapped and characterized iron-bound sulfur intermediates using cryo-mass spectrometry and X-ray absorption spectroscopy. Further support for the postulated intermediates in the chemically challenging conversion of H2S to thiosulfate and iron-bound catenated sulfur products is provided by EPR and resonance Raman spectroscopy in addition to density functional theory computational results. We speculate that the unusual sensitivity of skeletal muscle cytochrome c oxidase to sulfide poisoning in ethylmalonic encephalopathy, resulting from the deficiency in a mitochondrial sulfide oxidation enzyme, might be due to the concentration of H2S by myoglobin in this tissue.
Trever
T
Bostelaar
Victor
V
Vitvitsky
Jacques
J
Kumutima
Department of Pharmaceutical Science, Wayne State University , Detroit, Michigan 48201-2417, United States.
Brianne E
BE
Lewis
Pramod K
PK
Yadav
Department of Chemistry, University of Wisconsin , Madison, Wisconsin 53706, United States.
Thomas C
TC
Brunold
University of Bordeaux, IBGC, and CNRS, IBGC, UMR 5095 , F-33077 Bordeaux, France.
Milos
M
Filipovic
Nicolai
N
Lehnert
Department of Pharmaceutical Science, Wayne State University , Detroit, Michigan 48201-2417, United States.
Timothy L
TL
Stemmler
Ruma
R
Banerjee
D000818:Animals; D006736:Horses; D006862:Hydrogen Sulfide / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D007700:Kinetics; D009211:Myoglobin / Q000378:metabolism*; D010084:Oxidation-Reduction; D011485:Protein Binding
D009211:Myoglobin; D007501:Iron; D006862:Hydrogen Sulfide