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首页> 外文期刊>Biochemistry >Effects of nucleotides on the protein ligands to metals at the M2 and M3 metal-binding sites of the spinach chloroplast F1-ATPase.
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Effects of nucleotides on the protein ligands to metals at the M2 and M3 metal-binding sites of the spinach chloroplast F1-ATPase.

机译：核苷酸对菠菜叶绿体F1-ATPase M2和M3金属结合位点金属蛋白配体的影响。

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摘要

We have identified the most probable protein ligands at the catalytic M3 and noncatalytic M2 metal-binding sites in the spinach chloroplast F1-ATPase (CF1) and here propose possible residues in the protein sequence for these ligands in latent CF1 in the absence of nucleotide. The changes in the metal ligands at these sites upon binding of nucleotide to the N2 and N3 sites and upon activation of latent CF1 provide a possible molecular basis for inhibition of ATPase activity by free metal, for the lack of activity in the latent state, and for the gating mechanism of the ATPase H+ pump. To these ends, the Mg2+ analogue, vanadyl (VIV = O)2+, was used as a paramagnetic probe at the M2 and M3 metal-binding sites. EPR and ESEEM spectra of VO2+ were obtained, and simulations of the full EPR spectra imply the ligand sets at the different metal-binding sites. When VO2+ is added to CF1 in the absence of ATP, the most likely set of ligands at the M2 site are 1 ROH (alpha T176), 2 H2O, and 1 RCOO- (alpha D269 or alpha D270), where the suggested amino acid designations of the residues are given in parentheses according to the mitochondrial sequence. Evidence suggests a possible axial nitrogen ligand at this site (alpha K175). When the M2 site is filled by addition of VO2+ and ATP, the metal binds as a second species in which N2-bound ATP and M2-bound VO2+ form a monodentate complex with concomitant exchange of the equatorial protein ligands by 3 H2O.(ABSTRACT TRUNCATED AT 250 WORDS)
机译：我们已经在菠菜叶绿体F1-ATPase（CF1）中的催化M3和非催化M2金属结合位点确定了最可能的蛋白质配体，并提出了在无核苷酸的情况下在潜在CF1中这些配体的蛋白质序列中可能存在的残基。核苷酸结合到N2和N3位以及潜在CF1激活后，这些位点上金属配体的变化为游离金属抑制ATPase活性提供了可能的分子基础，因为在潜在状态下缺乏活性，并且用于ATPase H +泵的门控机制。为此，在M2和M3金属结合位点使用Mg2 +类似物，钒基（VIV = O）2+作为顺磁性探针。获得了VO2 +的EPR和ESEEM光谱，并且对整个EPR光谱的模拟表明配体在不同的金属结合位点处形成。当在不存在ATP的情况下将VO2 +添加到CF1时，在M2位点最可能的配体是1个ROH（alpha T176），2 H2O和1个RCOO-（alpha D269或alpha D270），其中建议的氨基酸根据线粒体序列，在括号中给出残基的名称。有证据表明该位点可能存在轴向氮配体（αK175）。当通过添加VO2 +和ATP填充M2位点时，金属结合成第二种，其中N2键合的ATP和M2键合的VO2 +形成单齿复合物，伴随着3 H2O交换赤道蛋白配体。（ 250字）

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