Measurement of in vivo Oxidation and Reduction by the Controlled Potential Method

Paul A. Loach*, Jennifer A. Culbert-Runquist

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The development of the controlled potential method for studying vivo redox reactions is described by showing some of the results of its first application to photosynthetic systems. Phototrap activity was shown to be operative only within the potential range from -0.I to + 0.5 V in R. rubrum and R. Spheroides. New results obtained by applying the technique to a complex enzymatic system, photophosphorylation, have shown that this activity is shut off at lower potential in parallel to shutting off phototrap activity. Optimal activity was found near o V while the activity was again totally quenched at higher potential with a midpoint of 0.30 V. This latter transition may reflect a component at the coupling site for electron transport and phosphorylation. A consideration of the possible effect of conformational changes on U′o values is given and valid usage of the controlled potential method is underscored.

Original languageEnglish (US)
Pages (from-to)427-437
Number of pages11
JournalBioelectrochemistry and Bioenergetics
Issue number3-4
StatePublished - Dec 1974

ASJC Scopus subject areas

  • Biophysics
  • Physical and Theoretical Chemistry
  • Electrochemistry


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