Comparing the temperature dependence of photosynthetic electron transfer in chloroflexus aurantiacus and rhodobactor sphaeroides reaction centers

Zhi Guo, Su Lin, Yueyong Xin, Haiyu Wang, Robert E. Blankenship, Neal Woodbury

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The process of electron transfer from the special pair, P, to the primary electron donor, HA, in quinone-depleted reaction centers (RCs) of Chloroflexus (Cf.) aurantiacus has been investigated over the temperature range from 10 to 295 K using time-resolved pump-probe spectroscopic techniques. The kinetics of the electron transfer reaction, P* → P+H A -, was found to be nonexponential, and the degree of nonexponentiality increased strongly as temperature decreased. The temperature-dependent behavior of electron transfer in Cf. aurantiacus RCs was compared with that of the purple bacterium Rhodobacter (Rb.) sphaeroides. Distinct transitions were found in the temperature-dependent kinetics of both Cf. aurantiacus and Rb. sphaeroides RCs, at around 220 and 160 K, respectively. Structural differences between these two RCs, which may be associated with those differences, are discussed. It is suggested that weaker protein-cofactor hydrogen bonding, stronger electrostatic interactions at the protein surface, and larger solvent interactions likely contribute to the higher transition temperature in Cf. aurantiacus RCs temperature-dependent kinetics compared with that of Rb. sphaeroides RCs. The reaction-diffusion model provides an accurate description for the room-temperature electron transfer kinetics in Cf. aurantiacus RCs with no free parameters, using coupling and reorganization energy values previously determined for Rb. sphaeroides, along with an experimental measure of protein conformational diffusion dynamics and an experimental literature value of the free energy gap between P* and P +HA -.

Original languageEnglish (US)
Pages (from-to)11230-11238
Number of pages9
JournalJournal of Physical Chemistry B
Volume115
Issue number38
DOIs
StatePublished - Sep 29 2011

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electron transfer
temperature dependence
Electrons
Kinetics
Proteins
Temperature
kinetics
Electron temperature
proteins
Coulomb interactions
Free energy
Superconducting transition temperature
Hydrogen bonds
temperature
Membrane Proteins
Energy gap
Pumps
quinones
bacteria
transition temperature

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Materials Chemistry
  • Surfaces, Coatings and Films

Cite this

Comparing the temperature dependence of photosynthetic electron transfer in chloroflexus aurantiacus and rhodobactor sphaeroides reaction centers. / Guo, Zhi; Lin, Su; Xin, Yueyong; Wang, Haiyu; Blankenship, Robert E.; Woodbury, Neal.

In: Journal of Physical Chemistry B, Vol. 115, No. 38, 29.09.2011, p. 11230-11238.

Research output: Contribution to journalArticle

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abstract = "The process of electron transfer from the special pair, P, to the primary electron donor, HA, in quinone-depleted reaction centers (RCs) of Chloroflexus (Cf.) aurantiacus has been investigated over the temperature range from 10 to 295 K using time-resolved pump-probe spectroscopic techniques. The kinetics of the electron transfer reaction, P* → P+H A -, was found to be nonexponential, and the degree of nonexponentiality increased strongly as temperature decreased. The temperature-dependent behavior of electron transfer in Cf. aurantiacus RCs was compared with that of the purple bacterium Rhodobacter (Rb.) sphaeroides. Distinct transitions were found in the temperature-dependent kinetics of both Cf. aurantiacus and Rb. sphaeroides RCs, at around 220 and 160 K, respectively. Structural differences between these two RCs, which may be associated with those differences, are discussed. It is suggested that weaker protein-cofactor hydrogen bonding, stronger electrostatic interactions at the protein surface, and larger solvent interactions likely contribute to the higher transition temperature in Cf. aurantiacus RCs temperature-dependent kinetics compared with that of Rb. sphaeroides RCs. The reaction-diffusion model provides an accurate description for the room-temperature electron transfer kinetics in Cf. aurantiacus RCs with no free parameters, using coupling and reorganization energy values previously determined for Rb. sphaeroides, along with an experimental measure of protein conformational diffusion dynamics and an experimental literature value of the free energy gap between P* and P +HA -.",
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