抗体片段在铂纳米粒子表面的构象重构

目的 最近在金纳米粒子（AuNPs）表面重构抗体片段的天然构象和功能的研究表明分子构象工程的可行性。本质上，分子构象工程就是要像蛋白质折叠一样，通过精确控制柔性非功能分子的构象使其产生新功能。本文在铂纳米粒子（PtNPs）表面重构抗体互补决定簇区（CDR）片段的天然构象和功能，旨在探索分子构象工程的普适性及揭示蛋白质结构-功能机制。方法 本文将抗溶菌酶抗体（cAB-lys3）中的CDR3片段（在单独存在时没有稳定构象和功能）通过两个Pt-S键偶联到PtNPs表面。CDR片段的天然构象和功能的恢复通过它对溶菌酶活性的抑制来表征。结果 通过多肽密度优化和表面聚乙二醇修饰，制得基于PtNPs的抗溶菌酶人工抗体（简称铂抗体）。溶菌酶活性测试结果表明，铂抗体可以特异性结合溶菌酶并显著抑制其活性。结论 本文第一次在PtNPs表面重构了蛋白质片段的天然构象并恢复了其功能，证明分子构象工程可作为一种通用方法制备基于纳米粒子的人工蛋白质。

Conformational Engineering of Antibody Fragments on The Surface of Platinum Nanoparticles

Objective Recent successful restoration of the native conformation and function of the complementary-determining regions (CDRs) of antibodies on gold nanoparticles (AuNPs) demonstrates that the era of molecular conformational engineering is dawning. Basically, molecular conformational engineering aims to precisely tune flexible non-functional molecules into special conformations to carry out novel functions, in the same way as protein folding. In order to explore the general applicability of molecular conformational engineering, as well as to reveal the mechanism of protein structure-function relationship, the objective of this work is to restore the native conformation and function of the CDRs of an antibody on platinum nanoparticles (PtNPs).Methods The CDR fragment of the anti-lysozyme antibody cAB-lys3, which has no stable conformation or function in free state, was conjugated onto the surface of PtNPs through two Pt-S bonds. The original antigen-recognizing function of the CDR restored on PtNPs was assessed by the specific inhibition of the enzymatic activity of lysozyme by the PtNP-CDR conjugates.Results After optimization of the peptide density on the surface of PtNPs and modification of PtNPs with polyethylene glycol (PEG), the resulted PtNP-based hybrid artificial antibody (PtNP-10PEG-30P1), dubbed Platinumbody, could bind specifically to lysozyme and significantly inhibit the activity of lysozyme.Conclusion This is the first time that the fragment of a protein could refold on PtNPs. Together with the previous Goldbody and Silverbody, current work demonstrates that artificial proteins could be generally created by restoration of the native conformation of natural proteins fragments on NPs.