SUBSTITUTION OF LANTHANIDES AT THE CALCIUM SITE(S) IN PHOTOSYSTEM-II AFFECTS ELECTRON-TRANSPORT FROM TYROSINE-Z TO P680+
SUBSTITUTION OF LANTHANIDES AT THE CALCIUM SITE(S) IN PHOTOSYSTEM-II AFFECTS ELECTRON-TRANSPORT FROM TYROSINE-Z TO P680+
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DOI：
10.1016/0005-2728(93)90057-m
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发表时间：
1993-03-01
期刊：
影响因子：
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通讯作者：
GHANOTAKIS, DF
中科院分区：
文献类型：
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作者：
BAKOU, A;GHANOTAKIS, DF
镧系元素取代光系统II中的Ca ~（2+）导致放氧活性的抑制。除了阻断从Mn-络合物到TyrZ+的电子传递之外，镧系元素的存在还影响从TyrZ到P680+的电子传递。后一种效应取决于两个因素：（i）三价镧系元素离子的离子半径;离子半径小于Ca 2+的镧系元素离子发挥更显著的抑制作用。(ii)系统的pH值;尽管镧系元素的存在对在pH6.0下TyrZ还原P680+具有强烈影响，但在pH7.5下没有观察到这种影响。pH滴定将pH效应归因于pK为6.5的氨基酸残基。
Substitution of lanthanides for Ca2+ in Photosystem II results in an inhibition of oxygen-evolution activity. In addition to blocking electron transport from the Mn-complex to TyrZ+, the presence of the lanthanides also affects electron transport from TyrZ to P680+. This latter effect depends on two factors: (i) The ionic radius of the trivalent lanthanide ion; lanthanide ions with an ionic radius smaller than that of Ca2+, exert a more pronounced inhibitory effect. (ii) The pH of the system; although the presence of lanthanides has a strong influence on the reduction of P680+ by TyrZ at pH 6.0, no such effect is observed at pH 7.5. A pH titration has attributed the pH effect to an amino acid residue with a pK of 6.5.