人肽基脯氨酰顺反异构酶基因的克隆、表达、纯化及热变性交联

蛋白质分子间交联是普遍存在的现象．然而，蛋白质交联的分子机理还不太清楚．为了进一步探测蛋白质交联的分子机理，以及交联能否在异源肽链间发生，本实验室克隆了人肽基脯氨酰顺反异构酶(human Peptidylproly-Cis-trans-isomerase，hPPI)cyclophilin cDNA基因，并纯化出了PPI蛋白．最后，将PPI和．lysozyme蛋白进行热变性交联实验，结果显示在同源和异源肽链间都有二聚体和多聚体形成．并证实蛋白质交联可经三步完成：1)蛋白质构象包括二级结构改变；2)形成分子间二硫键；3)形成分子间异肽键．

Cloning,expression,purification and protein cross linking during thermal unfolding of human peptidylprolyl cis trans isomerase cyclophilin

Protein interchain cross\|linking is a common phenomenon.However the molecular mechanisms for protein cross\|linking are not well understood.For further exploring the molecular mechanisms for protein cross\|linking, and detect if cross\|linking can happen in heterogeneous peptides, the investigation was extended with human peptidylprolyl\|cis\|trans\|isomerase cyclophilin (hPPI cyclophilin). hPPI cyclophilin cDNA was cloned and PPI protein was priufied.At last,hPPI cyclophilin and lysozyme were mixed during thermal unfolding.The observation revealed that heterodimer/oligomer formation was as common as homodimer/oligomer formation.It also proved protein cross\|linking can be accomplished in three concerted steps:(1) a change in protein conformation;(2) formation of interchain disulfide bonds; and (3) formation of interchain isopeptide cross\|links.