Gómez-Tamayo José C, Cordomí Arnau, Olivella Mireia, Mayol Eduardo, Fourmy Daniel, Pardo Leonardo
Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Barcelona, E-08193, Bellaterra, Spain.
Departament de Biologia de Sistemes, Universitat de Vic, Vic, 08500, Spain.
Protein Sci. 2016 Aug;25(8):1517-24. doi: 10.1002/pro.2955. Epub 2016 Jun 8.
The interactions of Met and Cys with other amino acid side chains have received little attention, in contrast to aromatic-aromatic, aromatic-aliphatic or/and aliphatic-aliphatic interactions. Precisely, these are the only amino acids that contain a sulfur atom, which is highly polarizable and, thus, likely to participate in strong Van der Waals interactions. Analysis of the interactions present in membrane protein crystal structures, together with the characterization of their strength in small-molecule model systems at the ab-initio level, predicts that Met-Met interactions are stronger than Met-Cys ≈ Met-Phe ≈ Cys-Phe interactions, stronger than Phe-Phe ≈ Phe-Leu interactions, stronger than the Met-Leu interaction, and stronger than Leu-Leu ≈ Cys-Leu interactions. These results show that sulfur-containing amino acids form stronger interactions than aromatic or aliphatic amino acids. Thus, these amino acids may provide additional driving forces for maintaining the 3D structure of membrane proteins and may provide functional specificity.
与芳香-芳香、芳香-脂肪族或/和脂肪族-脂肪族相互作用相比，甲硫氨酸（Met）和半胱氨酸（Cys）与其他氨基酸侧链的相互作用很少受到关注。确切地说，这是仅有的含有硫原子的氨基酸，硫原子具有高度极化性，因此可能参与强范德华相互作用。对膜蛋白晶体结构中存在的相互作用进行分析，并在从头算水平上对其在小分子模型系统中的强度进行表征，预测甲硫氨酸-甲硫氨酸相互作用强于甲硫氨酸-半胱氨酸≈甲硫氨酸-苯丙氨酸（Phe）≈半胱氨酸-苯丙氨酸相互作用，强于苯丙氨酸-苯丙氨酸≈苯丙氨酸-亮氨酸（Leu）相互作用，强于甲硫氨酸-亮氨酸相互作用，强于亮氨酸-亮氨酸≈半胱氨酸-亮氨酸相互作用。这些结果表明，含硫氨基酸形成的相互作用比芳香族或脂肪族氨基酸更强。因此，这些氨基酸可能为维持膜蛋白的三维结构提供额外的驱动力，并可能提供功能特异性。
