Nakagawa S H, Johansen N L, Madsen K, Schwartz T W, Tager H S
Department of Biochemistry and Molecular Biology, University of Chicago, Illinois.
Int J Pept Protein Res. 1993 Dec;42(6):578-84. doi: 10.1111/j.1399-3011.1993.tb00367.x.
To evaluate more thoroughly the importance of main-chain structure and flexibility in ligand interactions with the insulin receptor, we undertook to synthesize analogues with reduced peptide bonds in the COOH-terminal B chain domain of the hormone (a stable, but adjustable beta-strand region). By use of solid-phase, solution-phase and semisynthetic methods, analogues were prepared in which ArgB22 of des-octapeptide(B23-B30)-insulin was extended by the sequences Gly-Phe-psi (CH2-NH)-Phe-NH2, Gly-Gly-psi(CH2-NH)-Phe-Phe-NH2, Gly-Phe-psi (CH2-NH)-Phe-Phe-Thr-Pro-Ala-Thr-OH, and Gly-Phe-Phe-psi (CH2-NH)-Phe-Thr-Pro-Ala-Thr-OH, and were studied with respect to their abilities both to interact with the hepatocyte insulin receptor and to form soluble anion-stabilized hexamers in the presence of Co2+ and phenol. Additional analogues of des-pentapeptide(B26-B30)-insulin were also examined. Overall, our results show that, whereas all analogues retain considerable ability to form organized metal ion-coordinated complexes in solution, the reduction of peptide bonds both proximal and distal to the critical side chain of PheB25 results in analogues with severely diminished receptor binding potency. We conclude that the peptide carbonyls from both PheB24 and PheB25 are important for insulin-receptor interactions and that the structural organization of the region when insulin is bound to its receptor differs from that occurring during simple monomer-monomer and higher-order interactions of the hormone.
为了更全面地评估主链结构和灵活性在配体与胰岛素受体相互作用中的重要性，我们着手合成激素COOH末端B链结构域中肽键减少的类似物（一个稳定但可调节的β-链区域）。通过使用固相、液相和半合成方法，制备了类似物，其中去八肽（B23 - B30）-胰岛素中的ArgB22被Gly - Phe - ψ(CH2 - NH) - Phe - NH2、Gly - Gly - ψ(CH2 - NH) - Phe - Phe - NH2、Gly - Phe - ψ(CH2 - NH) - Phe - Phe - Thr - Pro - Ala - Thr - OH和Gly - Phe - Phe - ψ(CH2 - NH) - Phe - Thr - Pro - Ala - Thr - OH序列延伸，并研究了它们与肝细胞胰岛素受体相互作用以及在Co2+和苯酚存在下形成可溶性阴离子稳定六聚体的能力。还检查了去五肽（B26 - B30）-胰岛素的其他类似物。总体而言，我们的结果表明，尽管所有类似物在溶液中仍保留形成有组织的金属离子配位复合物的相当能力，但PheB25关键侧链近端和远端肽键的减少导致受体结合效力严重降低的类似物。我们得出结论，PheB24和PheB25的肽羰基对于胰岛素 - 受体相互作用很重要，并且胰岛素与其受体结合时该区域的结构组织不同于激素简单单体 - 单体和高阶相互作用期间发生的结构组织。
