title: Neuroglobin and cytoglobin as potential enzyme or substrate.
abstract: The possible enzymatic activities of neuro- and cytoglobin as well as their potential function as substrates in enzymatic reactions were studied. Neuro- and cytoglobin are found to show no appreciable superoxide dismutase, catalase, and peroxidase activities. However, the internal disulfide bond (CD7-D5) of human neuroglobin can be reduced by thioredoxin reductase. Furthermore, our in vivo and in vitro studies show that Escherichia coli cells contain an enzymatic reducing system that keeps the heme iron atom of neuroglobin in the Fe(2+) form in the presence of dioxygen despite the high autoxidation rate of the molecule. This reducing system needs a low-molecular-weight compound as co-factor. In vitro tests show that both NADH and NADPH can play this role. Furthermore, the reducing system is not specific for neuroglobin but allows the reduction of the ferric forms of other globins such as cytoglobin and myoglobin. A similar reducing system is present in eukaryotic tissue protein extracts.
authors.affiliation: Department of Physics of the University of Antwerp, Antwerp, Belgium.
authors.forename: F
authors.initials: F
authors.lastname: Trandafir
authors.forename: D
authors.initials: D
authors.lastname: Hoogewijs
authors.forename: F
authors.initials: F
authors.lastname: Altieri
authors.forename: P
authors.initials: P
authors.lastname: Rivetti di Val Cervo
authors.forename: K
authors.initials: K
authors.lastname: Ramser
authors.forename: S
authors.initials: S
authors.lastname: Van Doorslaer
authors.forename: J R
authors.initials: JR
authors.lastname: Vanfleteren
authors.forename: L
authors.initials: L
authors.lastname: Moens
authors.forename: S
authors.initials: S
authors.lastname: Dewilde
mesh_terms: D000818:Animals; D002374:Catalase / Q000378:metabolism; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D004798:Enzymes / Q000378:metabolism*; D005914:Globins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000737:chemistry / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000078787:Neuroglobin; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000378:metabolism; D013053:Spectrophotometry; D013059:Spectrum Analysis, Raman; D013379:Substrate Specificity; D013482:Superoxide Dismutase / Q000378:metabolism; D013880:Thioredoxin-Disulfide Reductase / Q000378:metabolism
chemical_list: D004220:Disulfides; D004798:Enzymes; D009419:Nerve Tissue Proteins; D000078787:Neuroglobin; D009243:NAD; D006418:Heme; D009249:NADP; D005914:Globins; D007501:Iron; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase; D013880:Thioredoxin-Disulfide Reductase