SUPPLEMENTARYINFORMATION Clausen & Junge 2004
On the contributions of YZ(very small!) and of Mn4Ca to absorption transients around a wavelength of 360 nm.
Oxidized minus reduced difference spectra of tyrosine (YZ) in PSII core particles, the contribution of tyrosine to a wavelength of 360 nm is very small.
Corrected difference spectra of YZox – YZ in oxygen-evolving PSII core particles at pH 5.5 (solid line) and in Mn-depleted centres at pH 9 (dotted line) and pH 5.7 (dashed line) in the UV, blue, green and red spectral regions.
Data from: Haumann,M., Mulkidjanian,A. & Junge,W.
Tyrosine-Z in oxygen evolving photosystem II: a hydrogen-bonded tyrosinate.
Biochemistry38, 1258-1267 (1999).
Data from: J. P. Dekker, H. J. van Gorkom, M. Brok L. Ouwehand
Opticalcharacterization of photosystem II electron donors.
Biochim. Biophys.Acta 764 (1984) 301-309.
Data from: W. Weiss G. Renger
Studies on the nature of the water-oxidizingenzyme. II. On the functional connection between the reaction-centercomplex and the water-oxidizing system Y in Photosystem II.
Biochim.Biophys. Acta 850 (1986) 173-183.
Oxidized minus reduced difference spectra of the catalytic centre of water oxidation:
the transitions S1S2 and S2S3produce about equal jumps and S0S1 almost nothing at a wavelength of 360 nm (arrows).
Difference spectra of the S-state transitions. The arrows indicate a wavelength of 360 nm.
Lavergne,J.
Improved UV-visible spectra of the S-transitions in the photosynthetic
oxygen-evolving system.
Biochim. Biophys. Acta1060, 175-188 (1991).
On the variation of the pattern of absorption transients at a wavelength of 360 nm between two preparations of PSII core particles.
Totally dark adapted PSII core particles were excited with a train of five laser flashes at ambient oxygen pressure. The magnitude of the rise upon the first flash of light varies considerably between different batches even if prepared by the same protocol.The variance reflects different proportionsin different preparations of reaction centres which are incompetent in oxygen evolution. The extent and the rate of the “undershoot” upon the third flash(indicative of the oxygen producing transition) are similar. Broadly speaking, the differences of the response to the first flash of light are insignificant for the analysis of water oxidation.
Controls for the reversibility of the effects which are induced by high oxygen pressure
FIG. A: This figure is related to the control trace (black) in Fig. 3 of the Letter to NATURE. The data were obtained with another batch of PSII core particles. The black transient represents the negative directed signal attributable to S3S0 from a sample which was kept under ambient oxygen pressure throughout. The red transient was recorded with a sample which was first exposed to high oxygen pressure (20 min), and thereafter decompressed to ambient oxygen pressure. Both transients were obtained with samples that were totallydark adapted.
The coincidence of both traces within noise limits proves the reversibility of the effects which are induced by exposure to high oxygen pressure.
FIG. B: This figure is related to the control trace (black) in Fig. 1 of the Letter . The black trace was obtained with a sample kept under ambient oxygen pressure, throughout. The red pattern was obtained with a sample which was first exposed to high oxygen pressure (20 min), and thereafter decompressed to ambient oxygen pressure. Both transients were obtained with samples that were repetitively dark adapted with dark intervals of 2 min duration between groups of five laser flashes. Although less pronounced than in totally dark adapted samples (see Figs. 1-4, A) the “undershoot” upon the third flash and the positive jumps upon the first, second and the fifth flash are evident. Deviations upon the first flash were discussed both in the Letter and further up in the Supplemental Material.
These features corroborate the reversibility of the effects which are induced by exposure to high oxygen pressure.