On the question of the identity of cytochrome b-560 in thylakoid stromal membranes |
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Authors: | G -S Tae R M Everly W A Cramer S A Madgwick P R Rich |
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Institution: | (1) Department of Biological Sciences, Purdue University, 47907 West Lafayette, IN, USA;(2) Glynn Research Institute, Bodmin, Corwall, UK |
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Abstract: | Stromal membranes enriched in PS I contain a low potential cytochrome with a reduced -band peak close to 560 nm. The identity of this cytochrome component has been ascribed either to a low potential form of the Photosystem II cytochrome b-559 or to a different cytochrome with a reduced -band of 560 nm. The half-bandwidth of the 560 nm component in stromal membranes is identical to that of purified cytochrome b-559. Western blots show that the stromal membranes contain an amount of PS II cytochrome b-559 -subunit that is more than sufficient to account for the cytochrome b-560 detected spectrophotometrically in these membranes. These immunochemical data and the similarity of (i) the spectral peaks, and (ii) the redox properties of low potential PS II cytochrome b-559 and the b-560 component, suggest that the simplest inference is that the cytochrome b-560 protein in stromal membranes is identical to the PS II cytochrome b-559.Abbreviations: A
absorbance
- cyt
cytochrome
- DCBQ
2,5-dichloro-p-benzoquinone
- Emx
midpoint potential at pH x
- hbw
half-bandwidth
- LP
low potential
- MD
menadiol
- MES
2-(N-morpholino)ethanesulfonic acid
- MHQ
methylhydroquinone
- PS I-PS II
photosystems I, II
- SDS-PAGE
sodium dodecylsulfate polyacrylamide gel electrophoresis |
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Keywords: | cytochrome b-559 Photosystem II reaction center thylakoid membrane assembly repair cycle |
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