Sökning: id:"swepub:oai:lup.lub.lu.se:05cd73e4-4947-4f92-81f3-0d8ae9fa2fa2" > The role of cytochr...
Fältnamn | Indikatorer | Metadata |
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000 | 04151naa a2200325 4500 | |
001 | oai:lup.lub.lu.se:05cd73e4-4947-4f92-81f3-0d8ae9fa2fa2 | |
003 | SwePub | |
008 | 160401s1999 | |||||||||||000 ||eng| | |
024 | 7 | a https://lup.lub.lu.se/record/1253582 URI |
024 | 7 | a https://doi.org/10.1016/S0005-2728(99)00044-42 DOI |
040 | a (SwePub)lu | |
041 | a engb eng | |
042 | 9 SwePub | |
072 | 7 | a art2 swepub-publicationtype |
072 | 7 | a ref2 swepub-contenttype |
100 | 1 | a Magnusson, Ann4 aut |
245 | 1 0 | a The role of cytochrome b559 and tyrosineD in protection against photoinhibition during in vivo photoactivation of Photosystem II |
264 | 1 | c 1999 |
520 | a In vivo photoactivation of Photosystem II was studied in the FUD39 mutant strain of the green alga Chlamydomonas reinhardtii which lacks the 23 kDa protein subunit involved in water oxidation. Dark grown cells, devoid of oxygen evolution, were illuminated at 0.8 μE m-2&#;s-1 light intensity which promotes optimal activation of oxygen evolution, or at 17 μE m-2&#;s-1, where photoactivation compete with deleterious photodamage. The involvement of the two redox active cofactors tyrosineD and cytochrome b559 during the photoactivation process, was investigated by EPR spectroscopy. TyrosineD on the D2 reaction center protein functions as auxiliary electron donor to the primary donor P680+ during the first minutes of photoactivation at 0.8 μE m-2&#;s-1 (compare with Rova et al., Biochemistry, 37 (1998) 11039-11045.). Here we show that also cytochrome b559 was rapidly oxidized during the first 10 min of photoactivation with a similar rate to tyrosineD. This implies that both cytochrome b559 and tyrosineD may function as auxiliary electron donors to P680+ and/or the oxidized tyrosine&#;Z on the D1 protein, to avoid photoinhibition before successful photoactivation was accomplished. As the catalytic water-oxidation successively became activated, TyrosineD remained oxidized while cytochrome b559 became rereduced to the equilibrium level that was observed prior to photoactivation. At 17 μE m-2&#;s-1 light intensity, where photoinhibition competes significantly with photoactivation, tyrosineD was very rapidly completely oxidized, after which the amount of oxidized tyrosineD decreased due to photoinhibition. In contrast, cytochrome b559 became reduced during the first 2 min of photoactivation at 17 μE m-2&#;s-1. After this, it was reoxidized, returning to the equilibrium level within 10 min. Thus, during in vivo photoactivation in high-light cytochrome b559 serves two functions. Initially, it probably oxidizes the reduced primary acceptor pheophytin, thereby relieving the acceptor side of reductive pressure, and later on it serves as auxiliary electron donor, preventing donor-side photoinhibition. | |
650 | 7 | a NATURVETENSKAPx Biologi0 (SwePub)1062 hsv//swe |
650 | 7 | a NATURAL SCIENCESx Biological Sciences0 (SwePub)1062 hsv//eng |
700 | 1 | a Rova, Maria4 aut |
700 | 1 | a Mamedov, Fikretu Lund University,Lunds universitet,Biokemi och Strukturbiologi,Centrum för Molekylär Proteinvetenskap,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Biochemistry and Structural Biology,Center for Molecular Protein Science,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH4 aut0 (Swepub:lu)biok-fma |
700 | 1 | a Fredriksson, Per-Olof4 aut |
700 | 1 | a Styring, Stenbjörnu Lund University,Lunds universitet,Biokemi och Strukturbiologi,Centrum för Molekylär Proteinvetenskap,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Biochemistry and Structural Biology,Center for Molecular Protein Science,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH4 aut0 (Swepub:lu)biok-sst |
710 | 2 | a Biokemi och Strukturbiologib Centrum för Molekylär Proteinvetenskap4 org |
773 | 0 | t Biochimica et Biophysica Acta - Bioenergeticsg 1411:1, s. 180-191q 1411:1<180-191x 0005-2728 |
856 | 4 | u http://dx.doi.org/10.1016/S0005-2728(99)00044-4y FULLTEXT |
856 | 4 8 | u https://lup.lub.lu.se/record/125358 |
856 | 4 8 | u https://doi.org/10.1016/S0005-2728(99)00044-4 |
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