Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.2.1.7 (BAL)
 1,977 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In uncoupled pig-heart mitochondria the rate of the reduction of duroquinone by succinate in the presence of cyanide is inhibited by about 50% by antimycin. This inhibition approaches completion when myxothiazol is also added or British anti-Lewisite-treated (BAL-treated) mitochondria are used. If mitochondria are replaced by isolated succinate:cytochrome c oxidoreductase, the inhibition by antimycin alone is complete. The reduction of a plastoquinone homologue with an isoprenoid side chain (plastoquinone-2) is strongly inhibited by antimycin with either mitochondria or succinate:cytochrome c reductase. The reduction by succinate of plastoquinone analogues with an n-alkyl side chain in the presence of mitochondria is inhibited neither by antimycin nor by myxothiazol, but is sensitive to the combined use of these two inhibitors. On the other hand, the reduction of the ubiquinone homologues Q2, Q4, Q6 and Q10 and an analogue, 2,3-dimethoxyl-5-n-decyl-6-methyl-1,4-benzoquinone, is not sensitive to any inhibitor of QH2:cytochrome c reductase tested or their combined use, either in normal or BAL-treated mitochondria or in isolated succinate:cytochrome c reductase. It is concluded that quinones with a ubiquinone ring can be reduced directly by succinate:Q reductase, whereas those with a plastoquinone ring can not. Reduction of the latter compounds requires participation of either center i or center o (Mitchell, P. (1975) FEBS Lett. 56, 1-6) or both, of QH2:cytochrome c oxidoreductase. It is proposed that a saturated side chain promotes, while an isoprenoid side chain prevents reduction of these compounds at center o.
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PMID:The effect of ring substituents on the mechanism of interaction of exogenous quinones with the mitochondrial respiratory chain. 301 95

Incubation of submitochondrial particles from bovine heart with 2,3-dimercaptopropanol (British antilewisite, BAL) results in inhibition of the respiratory chain between cytochromes b and c. BAL exerts no pronounced effect on the spectral and redox properties of cytochromes b566 and b562. In the BAL-treated submitochondrial particles antimycin brings about the bathochromic shift of the cytochrome b562 absorption alpha-band, but does not induce "extra-reduction" of cytochromes b. Upon a combined effect of antimycin and BAL the reduction of cytochromes b by succinate is inhibited. Whereas neither antimycin nor BAL alone prevents this reaction. The data obtained suggest the existence of two pathways of electron transfer from succinate to cytochromes b, one of which is blocked by antimycin and the other one by BAL. These two pathways form a cyclic loop of electron transport, in accordance with the Mitchell's "protonmotive CoQ-cycle" hypothesis. The traditional scheme of linear arrangement of the respiratory carriers in the succinate--cytochrom c reductase span of the electron transfer chain, as well as the Wikstrom--Berden's branched model, do not provide satisfactory explanation of the mode of BAL inhibitory action.
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PMID:[Effect of 2,3-dimercaptopropanol on electron transfer in the energy coupling site 2 of the respiratory chain: evidence for the Q-cycle hypothesis]. 624 33