Cyt. b-559 in Photosystem II
In chloroplasts, cytochrome b-559 is known to be associated with photosystem II. Though its role is not precisely understood, cyt b-559 functions probably on both the reducing and the oxidising sides of photo-system II. A high as well as a low potential form of cyt b-559 with mid-point potentials respectively from +350 mV to +400 mV and from +50 mV to +100 mV at pH 7.8 have been reported2 A range of redox forms may be observed in the intermediate region3 The high potential cyt b-559 requires the structural integrity of the thylakoid membrane, and its disruption causes cyt b-559 to be modified to lower potential forms. A heterogenous population of the high potential cyt b-559 has been reported. Based on biphasic chemical-induced oxidation kinetics, they have suggested that the high potential cytochrome b-559 exists in the thylakoid membrane in two different environments.
KeywordsPotential Form Donor Side Redox Form DMPC Liposome Light Induce Absorbance Change
Unable to display preview. Download preview PDF.
- 1.Butler, W.L. and Matsuda, H. (1983) Possible role of cytochrome b-559 in Photosystem II in The Oxygen Evolving System of Photosynthesis (Inoue, Y., Crofts, A.R., Govindjee Murata, N., Renger, G. and Satoh, K. eds) pp 113–122 Acad. Press, Japan.Google Scholar
- 3.Cramer, W.A. and Crofts, A.R. (1982) Electron and Proton Transport in: Photosynthesis. Vol.1 (Govindjee, ed.) pp 389–467 Acad. Press, New York.Google Scholar
- 5.Selak, M.A., Koch-Whitmarsh, B.E. and Whitmarsh, J. (1984) Evidence for a heterogenous population of high potential cytochrome b-559 in the thylakoid membrane in: Advances in Photosynthesis Research (Sybesma, C. ed.) Vol.1, pp 493–496 Martinus Nijhoff/Dr. W. Junk Publishers. The Hague, Netherlands.Google Scholar
- 7.Ghanotakis, D.F., Babcock, G.T. and Yocum, C.F. (1984) Structural and catalytic properties of the oxygen-evolving complex. Correlation of polypeptide and manganese release with the behaviour of Z in chloroplasts and a highly resolved preparation of the PS II complex. Biochim. Biophys. Acta. 765, 388–398.CrossRefGoogle Scholar
- 11.Velthuys, B.R. (1983) Spectrophotometric methods of probing the donor side of photosystem II in: The Oxygen Evolving System of Photosynthesis (Inoue, Y., Crofts, A.R., Govindjee Murata, N., Renger G. and Satoh, K. eds) pp 83–90. Acad. Press, Japan.Google Scholar
- 12.Ghanotakis, D.F., Yerkes, C.T. and Babcock, G.T. (1982) The role of reagents accelerating the deactivation reactions of water-splitting enzyme system Y (ADRY reagents) in destabilizing high potential oxidizing equivalents generated in chloroplast photosystem II. Biochim. Biophys. Acta. 682, 21–31.CrossRefGoogle Scholar
- 13.Yerkes, C.T. and Crofts, A.R. (1984) A mechanism for the ADRY induced photo-oxidation of cytochrome b-559 in: Advances in Photosynthesis Research (Sybesma, C. ed.) Vol.1, pp 489–492. Martinus Nijhoff/Dr. W. Junk Publishers, The Hague, Netherlands.Google Scholar
- 14.Tamura, N., Radmer, R., Lantz, S., Cammarata, K. and Cheniae, G. (1986) Depletion of photosystem II-extrinsic proteins. II. Analysis of the PS II/water oxidizing complex by measurements of N,N,N’,N’-tetramethyl-p-phenylenediamine oxidation following an actinic flash. Biochim. Biophys. Acta. 850, 369–379.CrossRefGoogle Scholar