EVALUATION OF THE COMPLEXITY OF CHARGE RECOMBINATION KINETICS IN PHOTOSYNTHETIC BACTERIA

Martin C. Woodle, Peggy L. Bustamante, Karen E. Zebrowski‐Morrison, Paul A Loach*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Abstract Improvements in instrumentation and methodology have allowed us to collect data of high signal to noise and reliability on the kinetics of recovery of both light‐induced absorbance changes and ESR signals at 95 K. The results obtained by the two methods are identical and can not be fit with a single exponential curve. The decay kinetics can be fit well with three exponential components which represent 85, 9 and 6% of the total change with rate constants of 29 s−1, 69 s−1 and 2.3 s−1, respectively. An interesting effect by molecular oxygen on the relaxation time of the donor cation radical was found by ESR measurements at low temperatures and higher microwave power. This interaction with oxygen could be blocked by addition of small amounts (e.g. 0.05%) of organic solvents such as ethanol. A variety of systems were examined including R. rubrum whole cells and chromatophores prepared from R. rubrum and Rps. sphaeroides. R. rubrum chromatophore samples were examined at high and low light intensities, at pH values from 6 to 10, in the presence and absence of air and after equilibration in D2O media. In all cases, the same decay kinetics were observed. It seems possible that the observed complex decay may be a characteristic of phototraps of all photosynthetic material and reflect fundamental structural and functional features yet to be uncovered.

Original languageEnglish (US)
Pages (from-to)525-531
Number of pages7
JournalPhotochemistry and Photobiology
Volume40
Issue number4
DOIs
StatePublished - Jan 1 1984

ASJC Scopus subject areas

  • Medicine(all)
  • Biochemistry
  • Physical and Theoretical Chemistry

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