Gallo P, Rossi F, Saviano M, Pedone C, Colonna G, Ragone R
Centro di Studio di Biocristallografia del C.N.R., Dipartimento di Chimica, Università degli Studi di Napoli "Federico II," via Mezzocannone 4, 80134 Naples, Italy.
J Biochem. 1998 Nov;124(5):880-5. doi: 10.1093/oxfordjournals.jbchem.a022202.
Like cyclosporin A, cyclolinopeptide A binds specifically bovine cyclophilin A, inhibiting its peptidyl-prolyl cis-trans isomerase activity. We describe here the protein interaction with several synthetic analogues of cyclolinopeptide A, which are either homodetic or disulphide bridged heterodetic cyclopeptides characterized by different ring dimensions, in terms of dissociation and inhibition constants evaluated by fluorescence and inhibition of the enzyme activity, respectively. Dissociation constants from fluorescence experiments are practically identical and about 20-fold lower than for cyclosporin A. On the other hand, inhibition constants differ from compound to compound and are higher than for cyclosporin A. This result is therefore difficult to rationalize, but we would suggest decoupling between binding and inhibitory ability of cyclopeptides. The Pro1 residue of cyclolinopeptide A seems to play a fundamental role in determining the inhibition of the rotamase activity of cyclophilin A, as the homodetic analogue lacking this residue does not show any inhibitory ability. Similarly, heterodetic analogues with a ring size smaller than 7 residues do not display inhibition. We presume that the sequence -Pro-Pro-Phe-Phe- and a ring size of 8 residues for homodetic cyclic peptides could be used as starting points in the targeted synthesis of cyclopeptides able to bind both cyclosporin A and calcineurin. The only peptide showing similar values of the dissociation and inhibition constant is cyclolinopeptide A. This compound can be considered a novel model for the molecular design of immunosuppressant drugs.
与环孢菌素A一样，环林肽A能特异性结合牛亲环蛋白A，抑制其肽基脯氨酰顺反异构酶活性。我们在此描述了环林肽A的几种合成类似物与蛋白质的相互作用，这些类似物要么是同型环肽，要么是具有不同环大小的二硫键桥联异型环肽，分别通过荧光和酶活性抑制来评估其解离常数和抑制常数。荧光实验得到的解离常数实际上是相同的，并且比环孢菌素A的解离常数低约20倍。另一方面，抑制常数因化合物而异，且高于环孢菌素A。因此，这一结果难以合理解释，但我们认为环肽的结合能力和抑制能力之间存在解耦现象。环林肽A的Pro1残基似乎在决定对亲环蛋白A的旋转异构酶活性的抑制中起关键作用，因为缺乏该残基的同型环肽类似物没有显示出任何抑制能力。同样，环大小小于7个残基的异型环肽类似物也没有表现出抑制作用。我们推测，同型环肽的-Pro-Pro-Phe-Phe-序列和8个残基的环大小可作为靶向合成既能结合环孢菌素A又能结合钙调神经磷酸酶的环肽的起点。唯一一种解离常数和抑制常数相似的肽是环林肽A。这种化合物可被视为免疫抑制剂药物分子设计的新模型。
