Department of Chemistry, College of Liberal Arts and Sciences, Tokyo Medical and Dental University, Chiba, 272-0827, Japan.
National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki, 305-8566, Japan.
Sci Rep. 2019 Mar 12;9(1):4217. doi: 10.1038/s41598-019-40889-9.
FTIR spectroscopy was employed to characterize the coordination structures of divalent cations (M = Ca or Mg) bound by L- and T-plastins, which contain two EF-hand motifs. We focused on the N-terminal headpieces in the L- and T-plastins to analyze the regions of COO stretching and amide-I in solution. The spectral profiles indicated that these headpieces have EF-hand calcium-binding sites because bands at 1551 cm and 1555 cm were observed for the bidentate coordination mode of Glu at the 12th position of the Ca-binding site of Ca-loaded L-plastin and T-plastin, respectively. The amide-I profile of the Mg-loaded L-plastin headpiece was identical with that of the apo L-plastin headpiece, meaning that L-plastin has a lower affinity for Mg. The amide-I profiles for apo, Mg-loaded and Ca-loaded T-plastin suggested that aggregation was generated in protein solution at a concentration of 1 mM. The implications of the FTIR spectral data for these plastin headpieces are discussed on the basis of data obtained for synthetic peptide analogs corresponding to the Ca-binding site.
傅里叶变换红外光谱（FTIR）被用于研究结合了二价阳离子（M=Ca 或 Mg）的 L-和 T-肌动蛋白的配位结构，这些二价阳离子由 L-和 T-肌动蛋白中的两个 EF 手基序结合。我们专注于 L-和 T-肌动蛋白的 N 端头部，以分析 COO 伸缩和酰胺-I 在溶液中的区域。光谱特征表明这些头部具有 EF 手钙结合位点，因为在负载 Ca 的 L-和 T-肌动蛋白的 Ca 结合位点的第 12 位的 Glu 的双齿配位模式下观察到了分别位于 1551cm-1 和 1555cm-1 的谱带。负载 Mg 的 L-肌动蛋白头部的酰胺-I 谱与 apo L-肌动蛋白头部的谱相同，这意味着 L-肌动蛋白对 Mg 的亲和力较低。apo、Mg 负载和 Ca 负载的 T-肌动蛋白的酰胺-I 谱表明，在 1mM 浓度的蛋白质溶液中发生了聚集。根据对应于 Ca 结合位点的合成肽类似物获得的数据，讨论了这些肌动蛋白头部的 FTIR 光谱数据的意义。
