Kaczmarek Krzysztof, Farina Biancamaria, Zubrzak Paweł, Jankowski Stefan, Zimecki Michał, Suder Piotr, Benedetti Ettore, Fattorusso Roberto, Saviano Michele, Zabrocki Janusz
Institute of Organic Chemistry, Faculty of Chemistry, Technical University of Łódź, Zeromskiego 116, 90-924 Łódź, Poland.
J Pept Sci. 2009 Mar;15(3):166-74. doi: 10.1002/psc.1099.
CLA, a natural, highly hydrophobic cyclic nonapeptide with sequence c(Pro(1)-Pro(2)-Phe(3)-Phe(4)-Leu(5)-Ile(6)-Ile(7)-Leu(8)-Val(9)-), isolated from linseed oil, was found to possess a strong immunosuppressive activity comparable, in low doses, with that of CsA, with a mechanism that depends on the inhibition of the interleukin-1 and interleukin-2 action. Structural analysis of CLA and its related compounds has underlined that the presence of the tetrapeptide Pro-Pro-Phe-Phe sequence, the Pro-Pro cis amide bond, and the 'edge-to-face' interaction are possible important features for the immunosuppressive activity of CLA. To evaluate the role and significance of 'edge-to-face' interaction in the process of molecular recognition by receptors, we have synthesised three linear precursors and three cyclic analogues of CLA, in which one or both Phe residues have been replaced by beta(3)Phe residues. A conformational analysis by NMR in CD(3)CN/H(2)O mixture has been carried out on the CLA analogue, in which Phe(3) has been replaced by a betaPhe, to study the influence of the mutation on the three-dimensional structure. All linear and cyclic CLA analogues containing betaPhe have been tested in the humoral and cellular immune response in vivo assays in mice. The peptide activities have been compared with CsA, as a reference drug.
共轭亚油酸（CLA）是一种天然的、高度疏水的环状九肽，其序列为c(Pro(1)-Pro(2)-Phe(3)-Phe(4)-Leu(5)-Ile(6)-Ile(7)-Leu(8)-Val(9)-)，从亚麻籽油中分离得到，发现其具有强大的免疫抑制活性，在低剂量下与环孢素A相当，其作用机制依赖于对白介素-1和白介素-2作用的抑制。对CLA及其相关化合物的结构分析强调，四肽Pro-Pro-Phe-Phe序列的存在、Pro-Pro顺式酰胺键以及“边对面”相互作用可能是CLA免疫抑制活性的重要特征。为了评估“边对面”相互作用在受体分子识别过程中的作用和意义，我们合成了CLA的三种线性前体和三种环状类似物，其中一个或两个苯丙氨酸残基已被β(3)苯丙氨酸残基取代。对CLA类似物进行了核磁共振（NMR）构象分析，其中Phe(3)已被β苯丙氨酸取代，以研究突变对三维结构的影响。所有含有β苯丙氨酸的线性和环状CLA类似物均已在小鼠体内的体液和细胞免疫反应测定中进行了测试。已将这些肽的活性与作为参考药物的环孢素A进行了比较。
