Jump to main content
Jump to site search

Issue 25, 2009
Previous Article Next Article

Electron transfer from A0 to A1 in Photosystem I from Chlamydomonas reinhardtii occurs in both the A and B branch with 25–30-ps lifetime

Author affiliations

Abstract

We have recorded transient absorption kinetics at 390 nm with picosecond resolution in order to observe electron transfer from the reduced primary acceptor, A0, to the secondary acceptor, A1, in wild type and mutated Photosystem I from Chlamydomonas reinhardtii. In the mutants, the methionine axial ligand to the primary electron acceptor in either the A- or B-branch of electron transfer cofactors, was replaced with histidine. Both of the mutations reduced the formation of a positive signal at 390 nm, characteristic of A1 to a level approximately half of that observed in wild type Photosystem I. It is concluded that in the mutated branch of Photosystem I, electron transfer from A0 to A1 does not occur. The absorption kinetics resulting from subtraction of either of the mutants’ traces from that of wild type is interpreted to reflect the kinetics of A- or B-side electron transfer from A0 to A1 in the the wild type Photosystem I. Each of these traces could be fitted with a monoexpoenential decay characterized by the same amplitude and 25–30-ps lifetime. The almost identical effect of both mutations on A1 formation confirm a similar engagement of both the A- ad B-branches in electron transfer to A1 in Photosystem I from C. reinhardtii. This observation is in contrast to the unidirectional electron transfer concluded from the studies on similar mutants of cyanobacterial Photosystem I.1 Thus, this contribution provides further evidence for functional differences between these two model Photosystems.

Graphical abstract: Electron transfer from A−0 to A1 in Photosystem I from Chlamydomonas reinhardtii occurs in both the A and B branch with 25–30-ps lifetime

Back to tab navigation
Please wait while Download options loads

Publication details

The article was received on 19 Dec 2008, accepted on 16 Mar 2009 and first published on 09 Apr 2009


Article type: Paper
DOI: 10.1039/B822938D
Citation: Phys. Chem. Chem. Phys., 2009,11, 5186-5191
  •   Request permissions

    Electron transfer from A0 to A1 in Photosystem I from Chlamydomonas reinhardtii occurs in both the A and B branch with 25–30-ps lifetime

    W. Giera, K. Gibasiewicz, V. M. Ramesh, S. Lin and A. Webber, Phys. Chem. Chem. Phys., 2009, 11, 5186
    DOI: 10.1039/B822938D

Search articles by author