Proton magnetic resonance studies on peptide fragments of troponin-C containing single calcium-binding sites.
Proton magnetic resonance studies on peptide fragments of troponin-C containing single calcium-binding sites.
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对含有单个钙结合位点的肌钙蛋白-C 肽片段的质子磁共振研究。
DOI：
10.1016/s0162-0134(00)80264-0
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发表时间：
1982
影响因子：
3.9
通讯作者：
Levine,BA
中科院分区：
文献类型：
--
作者：
Leavis,PC;Evans,JS;Levine,BA
质子磁共振波谱法已用于研究肌钙蛋白-C 的三个裂解片段的溶液构象，每个片段均包含单个 Ca(II) 结合位点，并对应于一级序列中的不同区域；即。 CB8（残基 46–77）、CB9（残基 85–134）和 TH2（残基 121–159）。尽管在没有金属离子的情况下，所有三种肽都缺乏明确的三级折叠，但一些光谱特征表明每种脱肽中存在局部构象限制。 Ca(II) 结合导致光谱变化，这与骨干运动限制的增加和采用更紧凑的构象一致。使用顺磁离子作为构象探针的研究支持了当前关于金属结合位点配体性质的观点。金属结合结构影响的性质和动力学表明，CB8 apo 肽中存在的构象限制提供了足够的 Ca(II) 结合构型。相比之下，CB9 和 TH2 肽表现出的光谱变化与 CB9 的螺旋 E（残基 94-102）区域和 TH2 的螺旋 H（残基 148-159）区域的局部结构增加一致。在 CB9 中，构象变化似乎也传递到螺旋 E 之前的序列部分（残基 87-93），螺旋 E 是肌钙蛋白-C 和肌钙蛋白-I 之间相互作用的推定位点。这些数据的讨论涉及肌钙蛋白-C 内长程（域间）相互作用的贡献以及 Ca(II) 结合对肌钙蛋白亚基蛋白质-蛋白质相互作用的调节。
Proton magnetic resonance spectroscopy has been employed to study the solution conformation of three cleavage fragments of troponin-C, each containing a single Ca(II)-binding site and corresponding to different regions in the primary sequence; viz. CB8 (residues 46–77), CB9 (residues 85–134) and TH2 (residues 121–159). Although all three peptides lack a well-defined tertiary fold in the absence of metal ions, several spectral features indicate the presence of local conformational constraints in each apopeptide. Ca(II) binding led to spectral changes consistent with increased restriction of backbone motility and the adoption of a more compact conformation. Studies using paramagnetic ions as conformational probes support current views concerning the nature of the ligands at the metal binding sites.The nature and kinetics of the structural influence of metal binding suggest that the conformational constraints existing in the CB8 apo-peptide provide an adequate Ca(II)-binding configuration. In contrast, the CB9 and TH2 peptides exhibit spectral changes consistent with an increased local structure in the region of helix E (residues 94–102) in the case of CB9 and helix H (residues 148–159) in the case of TH2. In CB9, conformation changes also appear to be transmitted to a portion of the sequence (residues 87–93) preceding helix E, a putative site of interaction between troponin-C and troponin-I. These data are discussed with reference to the contribution of long-range (interdomain) interactions within troponin-C and the modulation of troponin subunit protein-protein interactions by Ca(II) binding.