微悬臂梁检测三肽Gly-Gly-His与Cu2＋的相互作用过程

Interaction Between Tripeptide Gly-Gly-His and Cu^(2+) Probed by Microcantilevers

将三肽Gly-Gly-His(GGH)共价键合到MPA修饰的微悬臂梁表面,研究了肽与Cu2+的相互作用过程。研究发现,在Cu2+浓度较高时,Cu2+能快速与不同肽链上的羧基和咪唑环配位,并通过连锁反应诱导悬臂梁向镀金面偏转;而后肽链上的氮原子与Cu2+配位,同时构象发生变化,由直链转变成折叠状,进而增加链间的作用力使悬臂梁反向偏转;而Cu2+浓度低时不能实现连锁反应诱导悬臂梁表面快速的形成向内的拉力,直接通过构象变化推动悬臂梁反向偏转。考察了溶液pH值、Cl-浓度对GGH与Cu2+作用的影响,结果表明,在pH7.0的条件下GGH与Cu2+作用导致悬臂梁偏转最大。Cl-的存在会与Cu2+形成CuCl2x?x配合物不易与肽链结合。

Gly-Gly-His tripeptide modified microcantilever was developed by carbodiimide attachment of the Gly-Gly-His tripeptide onto a 3-mercaptopropionic acid（MPA） modified gold surface. The interaction of peptide with Cu2＋ ion was studied. At a relative high concentration of Cu2＋ , the cantilever bent toward the gold side initially as the N atom of imidazole ring and carboxyl group in different peptide coordinate with Cu2＋ , which results in a tensile surface stress. And then the reversed deflection of microcantilever was observed, which implies that the peptide-Cu2＋complex are formed with conformation transition. In another case, i. e. , at a relative low concentration of Cu2＋ , only the process of conformation transition was observed due to the coordination mode can not be formed initially. The influences of pH and salt concentration of the test solution on the performance of the sensor were studied. The results show that the maximum deflection was obtained at pH 7 and the bonding of Cu2＋ to the Gly-Gly-His tripeptide was inhibited due to the formation of CuClx2-x.