Zeder-Lutz G, Rauffer N, Altschuh D, Van Regenmortel M H
Institut de Biologie Moléculaire et Cellulaire du CNRS, UPR 9021, Laboratoire d'Immunochimie des Virus et des Peptides, Strasbourg, France.
J Immunol Methods. 1995 Jun 14;183(1):131-40. doi: 10.1016/0022-1759(95)00041-8.
The immunosuppressive cyclic undecapeptide cyclosporin A (CS) exists in various conformers in water. Up to 1 h is needed to reach maximum complex formation after mixing the drug with its receptor, cyclophilin or with a monoclonal antibody. Differences in the ability of CS and its analogs to bind to antibody or cyclophilin have been measured using the BIAcore. These experiments suggest that the rate-limiting step of complex formation is determined by the interconversion between different CS conformers existing in solution. The contribution to antibody binding of individual atomic groups of CS was evaluated by measuring the equilibrium affinity constants of analogs with the BIAcore. When the binding data were analyzed in terms of the known crystallographic structure of the CS/Fab complex, it could be shown that modifications of CS residues located in the central part of the binding site drastically affect affinity, while modifications of residues located at the periphery are more easily accommodated.
免疫抑制性环状十一肽环孢菌素A（CS）在水中以多种构象存在。将该药物与其受体亲环蛋白或单克隆抗体混合后，需要长达1小时才能达到最大复合物形成。使用BIAcore测量了CS及其类似物与抗体或亲环蛋白结合能力的差异。这些实验表明，复合物形成的限速步骤由溶液中不同CS构象之间的相互转化决定。通过用BIAcore测量类似物的平衡亲和常数，评估了CS单个原子基团对抗体结合的贡献。当根据CS/Fab复合物的已知晶体结构分析结合数据时，可以表明位于结合位点中心部分的CS残基修饰会极大地影响亲和力，而位于外围的残基修饰更容易被接受。
