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首页> 外文期刊>Biochemistry >Effect of Anions on the Photocycle of Halorhodopsin.Substitution of Chloride with Formate Anion
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Effect of Anions on the Photocycle of Halorhodopsin.Substitution of Chloride with Formate Anion

机译：阴离子对霍尔霍博甘露糖叶片光循环的影响。氯化物甲酸甲酯的阴离子

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摘要

Halorhodopsin from Natronomonas pharaonis is a light-driven chloride pump which transports a chloride anion across the plasma membrane following light absorption by a retinal chromophore which initiates a photocycle.It was shown that the chloride anion bound in the vicinity of retinal PSB can be replaced by several inorganic anions,including azide which converts the chloride pump into a proton pump and induces formation of an M-like intermediate detected in the bR photocycle but not in native halorhodopsin.Here we have studied the possibility of replacing the chloride anion with organic anions and have followed the photocycle under several conditions.It is revealed that the chloride can be replaced with a formate anion but not with larger organic anions such as acetate.Flash photolysis experiments detected in the formate pigment an M-like intermediate characterized by a lifetime much longer than that of the O intermediate.The lifetime of the M-like intermediate depends on the pH,and its decay is significantly accelerated at low pH.The decay rate exhibited a titration-like curve,suggesting that the protonation of a protein residue controls the rate of M decay.Similar behavior was detected in N.pharaonis pigments in which the chloride anion was replaced with NO_2~- and OCN~- anions.It is suggested that the formation of the M-like intermediate indicates branching pathways from the L intermediate or basic heterogeneity in the original pigment.
机译：来自NatronomonAnas的Halorhodopsin是一种光驱动的氯化物泵，其在通过引发光细胞的视网膜发色团之后将氯化物阴离子传送到血浆膜之后，所述视网膜发色团引起光细胞。可以通过包括将氯化物泵转换成质子泵的叠氮化物，并诱导在Br光上检测到的m样中间的形成，但不在天然卤冬豆荚中。它已经研究了用有机阴离子更换氯化物阴离子的可能性在几个条件下跟随了光循环。揭示氯化物可以用甲酸盐阴离子替换，但没有较大的有机阴离子，例如醋酸酯。在甲酸盐颜料中检测到的光解视图，其特征在于寿命长度比o中间体的。M样中间体的寿命取决于pH，和它S衰减在低pH下显着加速。衰减率表现出滴定样曲线，表明蛋白质残留物的质子化控制M衰减的速率。在氯化物阴离子被替换的N.pharaonis颜料中检测到相似的行为。用NO_2〜 - 和OCN〜阴离子。表明M样中间体的形成表明来自原始颜料中L中间或基本异质性的分支途径。

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  • 来源
    《Biochemistry》 |2005年第43期|共7页
  • 作者

    Keren Mevorat-Kaplan; Vlad Brumfeld; Martin Engelhard; Mordechai Sheves;

  • 作者单位

    Departments of Organic Chemistry and Plant Sciences Weizmann Institute of Science Rehovot 76100 Israel and Max-Planck-Institut fur Molekulare Physiologie Otto Hahn Strasse 11 44227 Dortmund Germany;

    Departments of Organic Chemistry and Plant Sciences Weizmann Institute of Science Rehovot 76100 Israel and Max-Planck-Institut fur Molekulare Physiologie Otto Hahn Strasse 11 44227 Dortmund Germany;

    Departments of Organic Chemistry and Plant Sciences Weizmann Institute of Science Rehovot 76100 Israel and Max-Planck-Institut fur Molekulare Physiologie Otto Hahn Strasse 11 44227 Dortmund Germany;

    Departments of Organic Chemistry and Plant Sciences Weizmann Institute of Science Rehovot 76100 Israel and Max-Planck-Institut fur Molekulare Physiologie Otto Hahn Strasse 11 44227 Dortmund Germany;

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  • 正文语种 eng
  • 中图分类 生物化学;
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