Turnover control of photosystem II: use of redox-active herbicides to form the S3 state
作者:Jeffrey R. Bocarsly、Gary W. Brudvig
DOI:10.1021/ja00051a006
日期:1992.12
0-4). While methods have been found to manipulate the system into S[sub 1] and S[sub2] in high yields, efficient production of the S[sub3] state in good yield at high concentration has not yet been achieved. Previous methods have suffered from the requirement of low protein concentration so that actinic flashes are saturating; the use of temperature to control S-state advancement under continuous illumination
光系统 II 的 O[sub 2] 演化中心包含一个活性位点四锰氧簇,催化两个水分子的四电子氧化为双氧,同时产生四个 H[sup +] 和四个电子。在催化转化期间,锰氧簇逐步通过五个中间氧化态,称为 S[sub i] 态 (i = 0-4)。尽管已发现以高产率将系统操纵成S[sub 1]和S[sub 2]的方法,但尚未实现在高浓度下以良好产率有效生产S[sub 3]态。以前的方法需要低蛋白质浓度,因此光化闪光会饱和。在连续光照下使用温度来控制 S 状态的推进,这会导致 S 状态加扰;或使用与 Q[sub B] 位点结合并将系统限制为一次周转的除草剂。作者在此描述了一种通过使用与 Q[sub B] 位点结合的电子接受除草剂在光系统 II 的高浓度样品中高产产生 S[sub 3] 态的方法。原则上,氧化还原活性除草剂可用于将 S 状态循环限制为任何所需的周转次数,前提是使用适当的除草剂。这项工作不仅对光系统
Low-Temperature Turnover Control of Photosystem II Using Novel Metal-Containing Redox-Active Herbicides
作者:Laba Karki、K. V. Lakshmi、Veronika A. Szalai、Gary W. Brudvig
DOI:10.1021/ja994138x
日期:2000.5.1
A novel approach of using metal-containing redox-active herbicides to prepare and study the light-induced intermediates of the photosystern II (PSII) photocycle is described. The redox-active herbicides feature an iron(III) ethylenediuninetetracetate [Fe-III-(EDTA)] electron-acceptor group linked to a Q(B)-site binding dimethylphenylurea moiety by a hydrocarbon spacer. Like the nitroxyl-based redox-active herbicides previously described (Bocarsly, J. R.; Brudvig, G. W. J. Am. Chem. Sec. 1992, 114, 9762-9767), metal-containing herbicides accept electrons from the donor side of PSII while bound to the Q(B) site and restrict the S-state cycling to two stable charge separations. The use of Fe-III-(EDTA) as an electron acceptor allows turnover at low temperatures. EPR studies of PSII upon continuous illumination at 225 K with 0.7 mM of redox-active herbicide, Fe-III-(EDTA) linked by an ethane spacer to a dimethylphenyl urea group (2), produced a stable two-step S-1 to S-3 advance of the O-2-evolving complex (OEC) and a stoichiometric reduction of the Fe-III-(EDTA) moiety of the herbicide, while a control sample with 0.02 InM DCMU [3-(3,4-dichlorophenyl)-1,1-dimethyl-urea] and 0.7 mM of 4 exhibited only a one-step SI to St advance of the OEC without significant reduction of the Fe-III-(EDTA) moiety of the herbicide. Similar EPR results were obtained for 7, Fe-III-(EDTA) linked Ca the dimethylphenylurea group by a pentane spacer. O-2-evolution inhibition studies show that appending the Fe-III-(EDTA) moiety to the phenylurea herbicide causes a significant decrease in the binding affinity compared to that of DCMU. On the basis of O-2-evolution studies with various herbicide derivatives and different PSII sample types, the observed decrease in binding affinities is attributed to the degree of accessibility of the Q(B)-binding pocket to the herbicides and to electrostatic and hydrophilicity factors. The present study describes the use of novel metal-containing herbicides in studying long-range electron transfer in PSII and in trapping photogenerated two-electron oxidized intermediate states of the O-2-evolving complex.
AKHTAR N.; BADAMI N. V.; CREMLYN J. W.; GOULDING K. J., PHOSPH. AND SULFUR,
作者:AKHTAR N.、 BADAMI N. V.、 CREMLYN J. W.、 GOULDING K. J.
DOI:——
日期:——
CN116903559
申请人:——
公开号:——
公开(公告)日:——
CHIVERS G. E.; CREMLYN R. J.; GUY R.; HONEYMAN R.; REYNOLDS P., AUSTRAL. J. CHEM. <AJCH-AS>, 1975, 28, NO 2, 413-419
作者:CHIVERS G. E.、 CREMLYN R. J.、 GUY R.、 HONEYMAN R.、 REYNOLDS P.