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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
21
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pubmed:dateCreated |
1986-9-17
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pubmed:abstractText |
The reactions of cytochrome b561 with other redox-active components of the adrenal chromaffin granule were examined using optical difference spectroscopy. It was shown that there is no direct electron transfer between the cytochrome and dopamine beta-hydroxylase, but that in the presence of ascorbate, turnover of dopamine beta-hydroxylase causes an oxidation of the cytochrome, which is partially reversed by the action of the mitochondrial NADH:A-. oxidoreductase. Thus, these three proteins may be functionally coupled via ascorbate. A quantitative study of the relationship between the redox state of the cytochrome and the ascorbate radical concentration measured by EPR showed that ascorbate reduces the cytochrome in a one-electron transfer reaction. Generation of a proton electrochemical gradient across the granule membrane causes only a small (20 mV) increase in the cytochrome midpoint potential suggesting the cytochrome is not a proton pump. The data are consistent with a model in which cytochrome b561, by reacting with ascorbate or ascorbate free radical on either side of the granule membrane, could couple the ascorbate-consuming reaction of the dopamine beta-hydroxylase inside the chromaffin granule to the ascorbate-regenerating reaction of the NADH:A-. oxidoreductase on the outer mitochondrial membrane. The H+-ATPase of the granule membrane could both drive the flow of electrons in the direction from cytosol to granule and replenish protons consumed by the turnover of dopamine beta-hydroxylase inside the granule.
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Ascorbic Acid,
http://linkedlifedata.com/resource/pubmed/chemical/Cytochrome b Group,
http://linkedlifedata.com/resource/pubmed/chemical/Dopamine beta-Hydroxylase,
http://linkedlifedata.com/resource/pubmed/chemical/Epinephrine,
http://linkedlifedata.com/resource/pubmed/chemical/Ethylmaleimide,
http://linkedlifedata.com/resource/pubmed/chemical/Free Radicals,
http://linkedlifedata.com/resource/pubmed/chemical/Fumarates,
http://linkedlifedata.com/resource/pubmed/chemical/Fusaric Acid,
http://linkedlifedata.com/resource/pubmed/chemical/NAD,
http://linkedlifedata.com/resource/pubmed/chemical/Norepinephrine,
http://linkedlifedata.com/resource/pubmed/chemical/Tyramine,
http://linkedlifedata.com/resource/pubmed/chemical/cytochrome b561,
http://linkedlifedata.com/resource/pubmed/chemical/fumaric acid
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pubmed:status |
MEDLINE
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pubmed:month |
Jul
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pubmed:issn |
0021-9258
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:day |
25
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pubmed:volume |
261
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
9739-45
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:3015904-Animals,
pubmed-meshheading:3015904-Ascorbic Acid,
pubmed-meshheading:3015904-Cattle,
pubmed-meshheading:3015904-Chromaffin Granules,
pubmed-meshheading:3015904-Chromaffin System,
pubmed-meshheading:3015904-Cytochrome b Group,
pubmed-meshheading:3015904-Dopamine,
pubmed-meshheading:3015904-Dopamine beta-Hydroxylase,
pubmed-meshheading:3015904-Electron Spin Resonance Spectroscopy,
pubmed-meshheading:3015904-Epinephrine,
pubmed-meshheading:3015904-Ethylmaleimide,
pubmed-meshheading:3015904-Free Radicals,
pubmed-meshheading:3015904-Fumarates,
pubmed-meshheading:3015904-Fusaric Acid,
pubmed-meshheading:3015904-Intracellular Membranes,
pubmed-meshheading:3015904-NAD,
pubmed-meshheading:3015904-Norepinephrine,
pubmed-meshheading:3015904-Oxidation-Reduction,
pubmed-meshheading:3015904-Spectrophotometry,
pubmed-meshheading:3015904-Tyramine
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pubmed:year |
1986
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pubmed:articleTitle |
Functional coupling between enzymes of the chromaffin granule membrane.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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