Time-Resolved Electrometric Study of the F→O Transition in Cytochrome c Oxidase. The Effect of Zn2+ Ions on the Positive Side of the Membrane

Sergey A. Siletsky, Robert B. Gennis

Research output: Contribution to journalArticlepeer-review

Abstract

Abstract: The effect of Zn2+ on the P-side of proteoliposomes containing membrane-incorporated Rhodobacter sphaeroides cytochrome c oxidase was investigated by the time-resolved electrometrics following a single electron injection into the enzyme prepared in the F state. The wild-type enzyme was examined along with the two mutants, N139D and D132N. All obtained data indicate that the primary effect of Zn2+ added from the P-side of the membrane is slowing of the pumped proton release from the proton loading site (PLS) to the bulk aqueous phase on the P-side of the membrane. The results strongly suggest the presence of two pathways by which the pumped proton can exit the protein from the PLS and of two separate binding sites for Zn2+. A model is presented to explain the influence of Zn2+ on the kinetics of membrane-potential generation by the wild-type COX, as well as by the N139D and D132N mutants.

Original languageEnglish (US)
Pages (from-to)105-122
Number of pages18
JournalBiochemistry (Moscow)
Volume86
Issue number1
DOIs
StatePublished - Jan 2021

Keywords

  • Rhodobacter sphaeroides
  • cytochrome aa
  • cytochrome c oxidase
  • electrogenic
  • proteoliposomes
  • proton pump
  • zinc ions

ASJC Scopus subject areas

  • Biochemistry

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