Proton ENDOR spectroscopy of the anion radicals of the chlorophyll primary electron acceptors in type I photosynthetic reaction centres

Autor: Michael C.W. Evans, Stephen E. J. Rigby, Irine P. Muhiuddin, Peter Heathcote, Stefano Santabarbara
Rok vydání: 2003
Předmět:
Zdroj: Chemical Physics. 294:319-328
ISSN: 0301-0104
DOI: 10.1016/s0301-0104(03)00284-2
Popis: Chlorin anion radicals have been produced by photoaccumulation of photosystem I and the type I reaction centresof the anoxygenic bacteria Chlorobium limicola and Heliobacterium chlorum. Proton electron nuclear double resonance(ENDOR) spectrometry of the photoaccumulated radicals demonstrates that the photoaccumulation technique is re-ducing chlorophyll anions rather than bacteriochlorophyll anions, indicating that photoaccumulation specifically re-duces the primary electron acceptors (A 0 ) in these anoxygenic reaction centres and is not reducing the antennabacteriochlorophylls. Detailed analysis of the in vivo proton ENDOR spectra in comparison with in vitro (bacte-rio)chlorophyll and (bacterio)pheophytin anion radicals points up differences between the environment of the A 0 inphotosystem I and the anoxygenic type I reaction centres. 2003 Elsevier B.V. All rights reserved. 1. IntroductionReaction centres are integral membrane pig-ment–protein complexes that convert the electro-magnetic energy of sunlight into chemicalpotential energy, thereby powering most of thebiological activity on the planet [1]. Reactioncentres are classed into one of two types accordingto the identity of the terminal electron acceptors[2]. In one group these are four-iron/four-sulphurclusters (Fe
Databáze: OpenAIRE
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