Issue 41, 2019

Why are photosynthetic reaction centres dimeric?

Abstract

All photosynthetic organisms convert solar energy into chemical energy through charge separation in dimeric reaction centres. It is unknown why early reaction centres dimerised and completely displaced their monomeric ancestors. Here, we discuss several proposed explanations for reaction-centre dimerism and conclude—with only weak assumptions about the primordial dimerisation event—that the most probable explanation for the dimerism is that it arose because it enhanced light-harvesting efficiency by deepening the excitonic trap, i.e., by enhancing the rate of exciton transfer from an antenna complex and decreasing the rate of back transfer. This effect would have outweighed the negative effect dimerisation would have had on charge transfer within the reaction centre. Our argument implies that dimerisation likely occurred after the evolution of the first antennas, and it explains why the lower-energy state of the special pair is bright.

Graphical abstract: Why are photosynthetic reaction centres dimeric?

Article information

Article type
Edge Article
Submitted
28 iyl 2019
Accepted
23 avq 2019
First published
26 avq 2019
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2019,10, 9576-9585

Why are photosynthetic reaction centres dimeric?

N. Taylor and I. Kassal, Chem. Sci., 2019, 10, 9576 DOI: 10.1039/C9SC03712H

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