AI Article Synopsis

  • The reduction of cytochrome b in beef-heart submitochondrial particles shows a biphasic pattern influenced by the redox state of a compound near the antimycin block.
  • HQNO can replace antimycin in experiments to saturate specific binding sites.
  • The slow phase of cytochrome b reduction is slowed down under anaerobic conditions and with BAL pretreatment, and the preference of cytochrome b-562 and b-566 reduction phases depends on the presence of antimycin and cyanide.

Article Abstract

(1) In agreement with Eisenbach and Gutman (Eisenbach, M. and Gutman, M. (1975) Eur. J. Biochem. 52, 107--116) the reduction of cytochrome b in beef-heart submitochondrial particles by succinate in the presence of antimycin was found to be biphasic, the relative amounts of fast and slow phases being dependent on the redox state of a compound located on the oxygen side of the antimycin block. (2) HQNO is a concentration sufficiently large to saturate the specific antimycin- and HQNO-binding sites can substitute for antimycin in these experiments. (3) The rate of the slow phase of the reduction of cytochrome b is decreased under anaerobic conditions and after pretreatment with 2,3-dimercaptopropanol (BAL). (4) In the presence of antimycin and cyanide, cytochrome b-562 is, to some extent, preferentially reduced in the rapid phase and b-566 in the slow phase. (5) The previously proposed regulatory effects of redox-sensitive components X and Y on the redox level and reduction kinetics, respectively, of cytochrome b are ascribed to the role of the Fe-S protein, when it is oxidized, in producing the reductant of cytochrome b by oxidation of QH2, and by the fact that when QH2 is bound to it, the reduced Fe-S protein cannot be oxidized by its natural oxidant, cytochrome c.

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Source
http://dx.doi.org/10.1016/0005-2728(81)90207-3DOI Listing

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