| Autor: |
Kultisheva MY; School of Biology, Lomonosov Moscow State University, Moscow, 119899, Russia. kulticheva@mars.biophys.msu.ru, Lovyagina ER, Kuznetsov AM, Solntsev MK, Semin BK, Ivanov II |
| Jazyk: |
angličtina |
| Zdroj: |
Biochemistry. Biokhimiia [Biochemistry (Mosc)] 2001 Jul; Vol. 66 (7), pp. 715-20. |
| DOI: |
10.1023/a:1010248309383 |
| Abstrakt: |
Extraction of the Mn-cluster from photosystem II (PS II) inhibits the main bands of thermoluminescence and induces a new AT-band at -20 degrees C. This band is attributed to the charge recombination between acceptor QA- and a redox-active histidine residue on the donor side of PS II. The effect of Mn(II) and Fe(II) cations as well as the artificial donors diphenylcarbazide and hydroxylamine on the AT-band of thermoluminescence was studied to elucidate the role of the redox-active His residue in binding to the Mn(II) and Fe(II). At the Mn/PS II reaction center (RC) ratio of 90 : 1 and Fe/PS II RC ratio of 120 : 1, treatment with Mn(II) and Fe(II) causes only 60% inhibition of the AT-band. Preliminary exposure of Mn-depleted PS II preparations to light in the presence of Mn(II) and Fe(II) causes binding of the cations to the high-affinity Mn-binding site, thereby inhibiting oxidation of the His residue involved in the AT-band formation. The efficiency of the AT-band quenching induced by diphenylcarbazide and hydroxylamine is almost an order of magnitude higher than the quenching efficiency of Mn(II) and Fe(II). Our results suggest that the redox-active His is not a ligand of the high-affinity site and does not participate in the electron transport from Mn(II) and Fe(II) to YZ. The concentration dependences of the AT-band inhibition by Mn(II) and Fe(II) coincide with each other, thereby implying specific interaction of Fe(II) with the donor side of PS II. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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