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Refined purification and further characterization of oxygen-evolving and Tris-treated Photosystem II particles from the thermophilic Cyanobacterium synechococcus sp.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Dekker, Jan P. Boekema, Egbert J. Witt, Heike Rögner, Matthias |
| Copyright Year | 1988 |
| Abstract | Highly active, monomeric and dimeric Photosystem II complexes were purified from the thermophilic cyanobacterium Synechococcus sp. by two sucrose density gradients, and the size, shape and mass of these complexes have been estimated (Rogner, M., Dekker, J.P., Boekema, E.J. and Witt, H.T. (1987) FEBS Lett. 219, 207–311). (1) Further purification could be obtained by ion-exchange chromatography, by which the 300 kDa monomer could be separated into a highly active, O2-evolving fraction, and a fraction without O2-evolving capacity, which has lost its extrinsic 34 kDa protein. Both showed very high reaction center activities as measured by the photoreduction of the primary quinone acceptor, QA, at 320 nm, being up to one reaction center per 31 Chl a molecules. (2) Tris-treatment yielded homogeneous 300 kDa particles which had lost their extrinsic 34 kDa polypeptide. Electron microscopy of this complex revealed very similar dimensions compared to the oxygen-evolving 300 kDa particle, except that the smallest dimension was decreased from about 6.5 nm to about 5.8 nm. This difference is attributed to the missing extrinsic 33 kDa protein, and the smallest dimension is attributed to the distance across the membrane. (3) Experiments are presented, allowing an estimation for the contribution of detergent to the other dimensions being about 2 × 1.5 nm for dodecyl β-d-maltoside. This leads to dimensions, corrected for detergent size, of 12.3 × 7.5 nm for the monomeric form of PS II and 12 × 15.5 nm for the dimeric form. (4) From some extracts a 35 kDa, chlorophyll-binding complex could be isolated which lacks the characteristic absorbance changes of QA and of Chl aII (P-680) and is therefore supposed to be a light-harvesting complex of cyanobacteria. (5) A model for the in vivo organization of PS II in cyanobacteria is discussed. |
| Starting Page | 307 |
| Ending Page | 318 |
| Page Count | 12 |
| File Format | PDF HTM / HTML |
| DOI | 10.1016/0005-2728(88)90006-0 |
| Volume Number | 936 |
| Alternate Webpage(s) | https://www.rug.nl/research/portal/files/14461758/1988BiochimBiophysActaDekker.pdf |
| Alternate Webpage(s) | https://doi.org/10.1016/0005-2728%2888%2990006-0 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
