10428
J. Phys. Chem. B 2004, 108, 10428-10439
Highly Efficient Spectral Hole-Burning in Oxygen-Evolving Photosystem II Preparations† Joseph L. Hughes,‡ Barry J. Prince,‡ Elmars Krausz,*,‡ Paul J. Smith,§ Ron J. Pace,§ and Hans Riesen⊥ Research School of Chemistry, The Australian National UniVersity, Canberra ACT 0200, Australia, Faculties Chemistry, The Australian National UniVersity, Canberra ACT 0200, Australia, and School of Physical, EnVironmental and Mathematical Sciences, UniVersity College, The UniVersity of New South Wales, ADFA, Canberra ACT 2600, Australia ReceiVed: February 18, 2004; In Final Form: May 14, 2004
We present the first report of highly efficient persistent spectral hole-burning in actiVe (oxygen-evolving) Photosystem II (PSII) preparations. Samples are poised in the S1 state of the Kok cycle, with the primary quinone (QA) either neutral or photoreduced to QA- via a low-temperature pre-illumination. Remarkably efficient hole-burning is observed within the chlorophyll Qy(0,0) absorption envelope in the wavelength range of 676695 nm. The hole-burning action spectrum of a sample poised in the S1(QA-) state is dominated by a narrow feature (∼40 cm-1) at 684 nm, where hole depths of 30% are attainable. The photoproduct for spectral holes burnt in this region is distributed across the ∼50 cm-1 absorption feature centered at 683.5 nm, independent of the excitation wavelength within this band. Saturated hole-burning experiments indicate weak electronphonon coupling near 684 nm but stronger coupling for holes burnt near 690 nm. Selective excitation near 690 nm of samples in the S1(QA) state also results in efficient QA- formation. Negligible hole-burning activity is observed at higher energies (
