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dc.contributor.authorDoyle, Michael
dc.contributor.authorKurtz, Donald Jr.
dc.contributor.authorNocel, Judith
dc.contributor.authorPickering, Ruth
dc.date.accessioned2021-11-16T19:51:18Z
dc.date.available2021-11-16T19:51:18Z
dc.date.issued1984-10
dc.identifier.citationhttps://doi.org/10.1016/S0021-9258(18)90749-0en_US
dc.identifier.issn1083-351X
dc.identifier.urihttps://hdl.handle.net/20.500.12588/727
dc.description.abstractIn anaerobic phosphate buffer, pH 6.3-7.5, deoxyhemerythrin is oxidized to semi-methemerythrin (semi-met) by excess sodium nitrite. This oxidation is quantitative as judged by EPR spectroscopy. Further oxidation to methemerythrin is not detected. The absorbance changes of hemerythrin during the oxidation are biphasic. The rate of the faster first phase is linearly dependent on [H+] and [NO2-] suggesting that the oxidant is nitrous acid rather than nitrite. During the slower second phase, the characteristic EPR spectrum of semi-methemerythrin appears. The first phase can be interpreted by a scheme in which nitrous acid transforms deoxyhemerythrin (FeIIFeII) to the semi-met nitrosyl adduct (FeIIFeIIINO) and hydroxide. Independent experiments confirm that the combination of semi-met plus NO produces an EPR-silent adduct. The rates of the absorbance changes for the second phase are nearly independent of nitrite concentration and pH in the range 6.3-7.5. This slower phase involves the transformation of the EPR-silent intermediate to the semi-met nitrite adduct (FeIIFeIIINO2-) and is consistent with rate-limiting dissociation of nitric oxide followed by rapid attachment of nitrite. Nitrite appears to be a unique oxidant of deoxyhemerythrin in that when employed in excess, the final, stable product is semi-met- rather than methemerythrin. The lack of reactivity of ethyl nitrite with deoxyhemerythrin suggests that HONO oxidizes deoxyhemerythrin via an "inner-sphere" process in contrast to oxidants such as Fe(CN)6(3-). A proposed generalization is that excesses of "inner-sphere" oxidants convert deoxy to (semi-met)R, which is stabilized with respect to (semi-met)R, which is stabilized with respect to (semi-met)0 and met because the oxidant and/or a product of the oxidant can bind to the iron site.
dc.language.isoen_USen_US
dc.publisherElsevieren_US
dc.relation.ispartofseriesJournal of Biological Chemistry;
dc.rightsAttribution 3.0 United States*
dc.rights.urihttp://creativecommons.org/licenses/by/3.0/us/*
dc.titleOxidation of Deoxyhemerythrin to the Semi-Met Level by Nitriteen_US
dc.typeArticleen_US
dc.description.departmentChemistryen_US


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Attribution 3.0 United States
Except where otherwise noted, this item's license is described as Attribution 3.0 United States