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dc.contributorWichita State University. Department of Chemistryen_US
dc.contributor.authorWanduragala, Srimevanen_US
dc.contributor.authorWimalasena, D. Shyamalien_US
dc.contributor.authorHaines, Donovan C.en_US
dc.contributor.authorKahol, Pawan K.en_US
dc.contributor.authorWimalasena, Kandategeen_US
dc.date.accessioned2012-02-06T17:17:24Z
dc.date.available2012-02-06T17:17:24Z
dc.date.issued2003-04-01en_US
dc.identifier12653566en_US
dc.identifier0370623en_US
dc.identifierNS39423en_US
dc.identifier.citationBiochemistry. 2003 Apr 1; 42(12): 3617-26.en_US
dc.identifier.issn0006-2960en_US
dc.identifier.urihttp://dx.doi.org/10.1021/bi0206661en_US
dc.identifier.urihttp://hdl.handle.net/10057/4419
dc.descriptionClick on the DOI link below to access the article (may not be free).en_US
dc.description.abstractThe transmembrane hemoprotein, cytochrome b(561) (b(561)), in the neuroendocrine secretory vesicles is shown to shuttle electrons from the cytosolic ascorbate (Asc) to the intravesicular matrix to provide reducing equivalents for the dopamine beta-monooxygenase (DbetaM) reaction. Intravesicular Asc may also play a role in relieving catecholamine-induced oxidative stress in catecholaminergic neurons. In the present study, we have examined the alteration of purified oxidized b(561) (b(561,ox)) under mild alkaline conditions to probe the structural and functional characteristics of the protein, using UV-vis and EPR spectroscopic and kinetic techniques. Our results show that low spin heme in oxidized b(561) (b(561,ox)) readily transforms to an altered high spin form and then slowly to an Asc nonreducible form, in a pH-, temperature-, and time-dependent manner, which can be described by single-exponential rate equations, A(t) = A(o)(1- e (-kt)) and A(t) = A(o)e(-kt), respectively. More than half of the Asc nonreducible altered b(561) could be converted back to the native b(561) by pH adjustment followed by dithionite reduction, suggesting the reversibility of the process. The heme center of the transformed Asc nonreducible protein is completely bleached instantaneously by dithionite in the presence of atmospheric oxygen, which appears to be mediated by molecular oxygen and/or hydrogen peroxide. These results demonstrate that the heme centers of the protein are susceptible to the pH-induced alteration and oxidative destruction, raising some questions regarding the proposed one alkaline labile, two-heme model of b(561) [Tsubaki, M.; Nakayama, M.; Okuyama, E.; Ichikawa, Y. (1997) J. Biol. Chem. 272, 23206-23210]. The pH-induced alteration and the destruction of heme under oxidative conditions may play a significant role in the amplification of oxidative stress in catecholaminergic neurons.en_US
dc.description.sponsorshipNINDS NIH HHSen_US
dc.format.extent3617-26en_US
dc.language.isoengen_US
dc.publisherAmerican Chemical Societyen_US
dc.relation.ispartofseriesBiochemistryen_US
dc.relation.ispartofseriesBiochemistryen_US
dc.sourceNLMen_US
dc.subjectIn Vitroen_US
dc.subjectResearch Support, U.S. Gov't, Non-P.H.S.en_US
dc.subjectResearch Support, U.S. Gov't, P.H.S.en_US
dc.subject.meshAnimalsen_US
dc.subject.meshCatecholamines/metabolismen_US
dc.subject.meshCattleen_US
dc.subject.meshChromaffin Granules/metabolismen_US
dc.subject.meshCytochrome b Group/chemistryen_US
dc.subject.meshElectron Spin Resonance Spectroscopyen_US
dc.subject.meshHeme/chemistryen_US
dc.subject.meshHydrogen-Ion Concentrationen_US
dc.subject.meshKineticsen_US
dc.subject.meshMolecular Structureen_US
dc.subject.meshNeurons/metabolismen_US
dc.subject.meshOxidation-Reductionen_US
dc.subject.meshOxidative Stressen_US
dc.subject.meshSpectrophotometryen_US
dc.subject.meshCytochrome b Group/metabolismen_US
dc.titlepH-induced alteration and oxidative destruction of heme in purified chromaffin granule cytochrome b(561): implications for the oxidative stress in catecholaminergic neuronsen_US
dc.typeArticleen_US
dc.coverage.spacialUnited Statesen_US
dc.description.versionpeer revieweden_US
dc.rights.holderCopyright © 2003 American Chemical Societyen_US


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