Jacob R, Bulleid N J, Naim H Y
Institute of Microbiology, Heinrich Heine University, Düsseldorf, Federal Republic of Germany.
J Biol Chem. 1995 Aug 4;270(31):18678-84. doi: 10.1074/jbc.270.31.18678.
The folding of human intestinal prolactase-phlorizin hydrolase (pro-LPH) has been analyzed in a cell-free transcription/translation system. In the presence of the thiol oxidant GSSG, disulfide bond formation in pro-LPH can be promoted concomitant with the binding of the molecule to a conformation-specific monoclonal anti-LPH antibody. Under these conditions, pro-LPH does not bind to the molecular chaperone BiP. In the absence of GSSG, on the other hand, pro-LPH does not bind to the monoclonal anti-LPH antibody, but can be immunoprecipitated with a polyclonal antibody that is directed against a denatured form of the enzyme. In this case, interaction of pro-LPH with immunoglobulin heavy chain binding protein can be discerned. The results demonstrate the existence of intramolecular disulfide bonds that are essential for the promotion of pro-LPH to a native conformation. Furthermore, BiP is involved in the folding events of pro-LPH.
已在无细胞转录/翻译系统中分析了人肠型前乳糖酶-根皮苷水解酶（pro-LPH）的折叠情况。在硫醇氧化剂谷胱甘肽二硫化物（GSSG）存在的情况下，pro-LPH中的二硫键形成可与该分子与构象特异性单克隆抗LPH抗体的结合同时促进。在这些条件下，pro-LPH不与分子伴侣BiP结合。另一方面，在没有GSSG的情况下，pro-LPH不与单克隆抗LPH抗体结合，但可以用针对该酶变性形式的多克隆抗体进行免疫沉淀。在这种情况下，可以识别pro-LPH与免疫球蛋白重链结合蛋白的相互作用。结果表明存在分子内二硫键，这些二硫键对于将pro-LPH促进至天然构象至关重要。此外，BiP参与了pro-LPH的折叠过程。
