Johnson W C, Pagano T G, Basson C T, Madri J A, Gooley P, Armitage I M
Department of Biochemistry and Biophysics, Oregon State University, Corvallis 97331-6503.
Biochemistry. 1993 Jan 12;32(1):268-73. doi: 10.1021/bi00052a034.
The sequence Arg-Gly-Asp (RGD) has been found to be the consensus sequence of matrix proteins for binding cell surface receptors (integrins). Studies with synthetic peptides containing the RGD sequence show that the biological activity of these oligopeptides is removed upon a conservative substitution of Glu for Asp in the RGD sequence. Two-dimensional 1H NMR methods were used to investigate the secondary structures in aqueous solution for two such oligopeptides of differing biological activity. The sequence Tyr-Gly-Arg-Gly-Asp-Ser-Pro, which binds to selected integrins, is found to assume a type II beta-turn at both pH 4 and 7. In contrast, the sequence Tyr-Gly-Arg-Gly-Glu-Ser-Pro, which does not interfere with integrin-mediated cell attachment, is found to assume a type I or III beta-turn at both pH 4 and 7. This comparison confirms not only that oligopeptides can assume a secondary structure in aqueous solution, but also that these structures may be important to biological functions.
已发现序列精氨酸-甘氨酸-天冬氨酸（RGD）是基质蛋白与细胞表面受体（整合素）结合的共有序列。对含RGD序列的合成肽的研究表明，当RGD序列中的天冬氨酸被谷氨酸保守取代时，这些寡肽的生物活性就会丧失。采用二维¹H NMR方法研究了两种具有不同生物活性的此类寡肽在水溶液中的二级结构。与选定整合素结合的序列酪氨酸-甘氨酸-精氨酸-甘氨酸-天冬氨酸-丝氨酸-脯氨酸在pH 4和pH 7时均呈现II型β-转角。相反，不干扰整合素介导的细胞附着的序列酪氨酸-甘氨酸-精氨酸-甘氨酸-谷氨酸-丝氨酸-脯氨酸在pH 4和pH 7时均呈现I型或III型β-转角。这种比较不仅证实了寡肽在水溶液中可以呈现二级结构，而且这些结构可能对生物学功能很重要。
