title: Catalase as a sulfide-sulfur oxido-reductase: An ancient (and modern?) regulator of reactive sulfur species (RSS).
abstract: Catalase is well-known as an antioxidant dismutating H2O2to O2and H2O. However, catalases evolved when metabolism was largely sulfur-based, long before O2and reactive oxygen species (ROS) became abundant, suggesting catalase metabolizes reactive sulfide species (RSS). Here we examine catalase metabolism of H2Sn, the sulfur analog of H2O2, hydrogen sulfide (H2S) and other sulfur-bearing molecules using H2S-specific amperometric electrodes and fluorophores to measure polysulfides (H2Sn; SSP4) and ROS (dichlorofluorescein, DCF). Catalase eliminated H2Sn, but did not anaerobically generate H2S, the expected product of dismutation. Instead, catalase concentration- and oxygen-dependently metabolized H2S and in so doing acted as a sulfide oxidase with a P50of 20mmHg. H2O2had little effect on catalase-mediated H2S metabolism but in the presence of the catalase inhibitor, sodium azide (Az), H2O2rapidly and efficiently expedited H2S metabolism in both normoxia and hypoxia suggesting H2O2is an effective electron acceptor in this reaction. Unexpectedly, catalase concentration-dependently generated H2S from dithiothreitol (DTT) in both normoxia and hypoxia, concomitantly oxidizing H2S in the presence of O2. H2S production from DTT was inhibited by carbon monoxide and augmented by NADPH suggesting that catalase heme-iron is the catalytic site and that NADPH provides reducing equivalents. Catalase also generated H2S from garlic oil, diallyltrisulfide, thioredoxin and sulfur dioxide, but not from sulfite, metabisulfite, carbonyl sulfide, cysteine, cystine, glutathione or oxidized glutathione. Oxidase activity was also present in catalase from Aspergillus niger. These results show that catalase can act as either a sulfide oxidase or sulfur reductase and they suggest that these activities likely played a prominent role in sulfur metabolism during evolution and may continue do so in modern cells as well. This also appears to be the first observation of catalase reductase activity independent of peroxide dismutation.
authors.affiliation: Indiana University School of Medicine - South Bend, South Bend, IN 46617, USA. Electronic address: olson.1@nd.edu.
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Olson
authors.affiliation: Indiana University School of Medicine - South Bend, South Bend, IN 46617, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Indiana University School of Medicine - South Bend, South Bend, IN 46617, USA; Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA.
authors.forename: Eric R
authors.initials: ER
authors.lastname: DeLeon
authors.affiliation: Indiana University School of Medicine - South Bend, South Bend, IN 46617, USA.
authors.forename: Maaz
authors.initials: M
authors.lastname: Arif
authors.affiliation: Indiana University School of Medicine - South Bend, South Bend, IN 46617, USA.
authors.forename: Faihaan
authors.initials: F
authors.lastname: Arif
authors.affiliation: Indiana University School of Medicine - South Bend, South Bend, IN 46617, USA.
authors.forename: Nitin
authors.initials: N
authors.lastname: Arora
authors.affiliation: Central Arkansas Veteran's Healthcare System, Little Rock, AR 72205, USA; Departments of Medicine and Biochemistry, University of Arkansas for Medical Sciences, Little Rock, AR 72202, USA.
authors.forename: Karl D
authors.initials: KD
authors.lastname: Straub
mesh_terms: D000498:Allyl Compounds / Q000378:metabolism; D000693:Anaerobiosis; D001234:Aspergillus niger / Q000201:enzymology*; D002374:Catalase / Q000378:metabolism*; D005452:Fluoresceins / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D006862:Hydrogen Sulfide / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013440:Sulfides / Q000378:metabolism
chemical_list: D000498:Allyl Compounds; D005452:Fluoresceins; D005656:Fungal Proteins; D017382:Reactive Oxygen Species; D013440:Sulfides; C042577:diallyl trisulfide; C037631:2',7'-dichlorofluorescein; C038491:allyl sulfide; C032915:polysulfide; D002374:Catalase; D006862:Hydrogen Sulfide
keywords: Aspergillus niger; Evolution; Garlic; Hydrogen sulfide; Polysulfide; Reactive oxygen species; Thioredoxin