Centrin: its secondary structure in the presence and absence of cations.
Centrin: its secondary structure in the presence and absence of cations.
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Centrin：存在和不存在阳离子时的二级结构。
DOI：
10.1021/bi0157971
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发表时间：
2002
期刊：
影响因子：
2.9
通讯作者：
Salisbury,JeffreyL
中科院分区：
文献类型：
--
作者：
Pastrana-Rios,Belinda;Ocaña,Wanda;Rios,Michelle;Vargas,GermanLorenzo;Ysa,Ginny;Poynter,Gregory;Tapia,Javier;Salisbury,JeffreyL
Centrin 是一种低分子量 (20 kDa) 蛋白质，属于钙结合蛋白 EF-hand 超家族。使用傅里叶变换红外（FT-IR）和圆二色（CD）光谱研究了阳离子和衣藻中心蛋白之间的相互作用的局部和整体变化。研究的 FT-IR 光谱特征包括酰胺 I‘ 波段和天冬氨酸残基的侧链吸光度，这些残基几乎完全位于 1700−1500 cm-1 光谱区域的钙结合位点。酰胺 I’ 带对蛋白质二级结构的变化非常敏感，并且观察到在存在和不存在钙的情况下从 1626.5 cm-1 移动到 1642.7 cm-1。这些光谱带很复杂，并使用二维傅里叶变换红外 (2D-FT-IR) 相关性以及曲线拟合程序进行了进一步研究。使用这些方法，确定了全中心蛋白和脱皮中心蛋白的二级结构贡献。在存在和不存在阳离子的情况下，中心蛋白中的 α-螺旋含量分别确定为 60%−53%。此外，在存在和不存在阳离子的情况下，β链含量确定为12%−36%，而无规卷曲成分几乎分别保持在7%−13.5%。侧链带的变化主要是由于天冬氨酸与阳离子的单齿配位所致。对于脱皮中心蛋白和全中心蛋白，分别观察到从 1565 cm-1 到 1569 cm-1 约 4 cm-1 的偏移（对于 Asp 中的 COO 反对称拉伸）。热依赖性揭示了脱皮中心蛋白的可逆构象转变温度为 37 °C，全中心蛋白为 45 °C，这表明全中心蛋白具有更高的稳定性。
Centrin is a low molecular mass (20 kDa) protein that belongs to the EF-hand superfamily of calcium-binding proteins. Local and overall changes were investigated for interactions between cations andChlamydomonascentrin using Fourier transform infrared (FT-IR) and circular dichroic (CD) spectroscopies. FT-IR spectral features studied included the amide I‘ band and the side-chain absorbances for aspartate residues located almost exclusively at the calcium-binding sites in the spectral region of 1700−1500 cm-1. The amide I‘ band is exquisitely sensitive to changes in protein secondary structure and is observed to shift from 1626.5 to 1642.7 cm-1in the presence and absence of calcium. These spectral bands are complex and were further studied using two-dimensional Fourier transform infrared (2D-FT-IR) correlation along with curve-fitting routines. Using these methods the secondary structure contributions were determined for holocentrin and apocentrin. The α-helical content in centrin was determined to be 60%−53% in the presence and absence of cations, respectively. Furthermore, the β-strand content was determined to be 12%−36%, while the random coil component remained almost constant at 7%−13.5% in the presence and absence of cations, respectively. Changes in the side-chain band are mostly due to the monodentate coordination of aspartate to the cation. A shift of ∼4 cm-1(for the COO-antisymmetric stretch in Asp) from 1565 to 1569 cm-1is observed for apocentrin and holocentrin, respectively. Thermal dependence revealed reversible conformational transition temperatures for apocentrin at 37 °C and holocentrin at 45 °C, suggesting greater stability for holocentrin.