Document Detail

Protein ubiquinone interaction. Synthesis and biological properties of 5-alkyl ubiquinone derivatives.
MedLine Citation:
PMID:  7961719     Owner:  NLM     Status:  MEDLINE    
For the investigation of the protein-ubiquinone interaction in the succinate-cytochrome c reductase region of the bovine heart mitochondrial electron transport chain, a series of 5-alkyl-substituted ubiquinone derivatives (5-R-Q0C10) were synthesized and characterized. Syntheses of 5-ethyl-Q0C10, 5-propyl-Q0C10, 5-isopropyl-Q0C10, and 5-butyl-Q0C10, were archived through radical coupling reactions between 2,3-dimethoxy-6-decyl-1,4-benzoquinone (5-H-Q0C10) and the corresponding alkanoyl peroxides. Although the spectral and redox properties of 5-R-Q0C10 are very similar to those of 5-methyl-2,3 dimethoxy-6-decyl-1,4-benzoquinone, the biological electron transfer efficiencies of these derivatives differ significantly. The reducibility of these derivatives by succinate, as measured with succinate-Q reductase and the oxidizability as measured by ubiquinol-cytochrome c reductase, decreased as the size of the substituents increased. 5-Ethyl-Q0C10 has about 50% of the activity of 5-methyl-2,3-dimethoxy-6-decyl-1,4-benzoquinone, whereas molecules with 5-alkyl groups of three or more carbon atoms are virtually inactive as electron acceptors for succinate-Q reductase. Reduced form of the derivative with no substituent at the 5-position, 5-H derivative is more effectively oxidized by ubiquinol-cytochrome c reductase than does the 5-methyl derivative, the native form. The oxidation of 5-H derivative is in a concentration-dependent manner at low concentrations but exhibits a substrate inhibition at higher concentrations. No such substrate inhibition is observed when other 5-substituted Q derivatives are used. 5-H derivative is a better electron acceptor for succinate-Q reductase than any other Q derivatives and does not show substrate inhibition, even at high concentrations. These results indicate that the binding environment of the benzoquinone ring in succinate-Q reductase is more specific than that of ubiquinol-cytochrome c reductase.
D Y He; L Yu; C A Yu
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  269     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1994 Nov 
Date Detail:
Created Date:  1994-12-16     Completed Date:  1994-12-16     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  27885-8     Citation Subset:  IM    
Department of Biochemistry, Oklahoma State University, Stillwater 74078.
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MeSH Terms
Electron Transport Complex II
Electron Transport Complex III / metabolism*
Indicators and Reagents
Multienzyme Complexes / metabolism*
Oxidoreductases / metabolism*
Structure-Activity Relationship
Succinate Cytochrome c Oxidoreductase / metabolism*
Succinate Dehydrogenase / metabolism*
Ubiquinone / analogs & derivatives*,  chemical synthesis*,  metabolism,  pharmacology
Grant Support
Reg. No./Substance:
0/Indicators and Reagents; 0/Multienzyme Complexes; 1339-63-5/Ubiquinone; EC 1.-/Oxidoreductases; EC 1.-/Succinate Cytochrome c Oxidoreductase; EC Transport Complex III; EC Transport Complex II; EC Dehydrogenase

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