Dependency on Environmental Redox Potential of Photophosphorylation in Rhodopseudomonas spheroides

J. A. Culbert-Runquist, R. M. Hadsell*, P. A. Loach

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


An all-glass apparatus was constructed which allowed measurement of photophosphorylation at different redox potentials. The luciferin-luciferase assay was adapted so that ATP could be measured within a few minutes of its formation. Optimal photophosphorylation activity in chromatophores from Rhodopseudomonas spheroides under saturating white light was 150 μmol of ATP/hr per mg of bacteriochlorophyll and was found at an environmental redox potential near 0 V at pH 7.9. Activity decreased at lower potentials, with a midpoint for the transition occurring at –0.09 V at pH 7.9 and –0.03 V at pH 7.0. The latter value is close to that for decreased phototrap activity measured previously by following light-induced absorbance changes (E0′ = –0.02 V). Photophosphorylation activity also decreased at higher potential with an apparent midpoint at 0.30 V. This is the first measurement of such a redox-linked component in photophosphorylation.

Original languageEnglish (US)
Pages (from-to)3508-3514
Number of pages7
Issue number18
StatePublished - Aug 1 1973

ASJC Scopus subject areas

  • Biochemistry


Dive into the research topics of 'Dependency on Environmental Redox Potential of Photophosphorylation in Rhodopseudomonas spheroides'. Together they form a unique fingerprint.

Cite this