新型人生长激素释放激素类似肽的生物学活性研究

Bioactive study of six novel GHRH analogs

目的通过生长激素释放激素肽(GHRH)改构寻找新的人生长激素释放激素类似肽(hGHRH Analog)。方法以固相合成技术合成6种新型N端和(或)C端改构的GHRH类似肽Pro-Pro-hGHRH(1-44)、ProhGHRH(1-44)、1Pro-GHRH(2-44)、Pro-Pro-hGHRH(1-44)-Gly-Gly-Cys、Pro-hGHRH(1-44)-GlyGly-Cys和1Pro-GHRH(2-44)-Gly-Gly-Cys。用C18反相高效液相色谱法和电喷雾质谱法检验其纯度和精确分子量。通过大鼠垂体刺激实验测定这些肽的鼠生长激素和其他垂体激素的释放值。结果通过N端ProPro-或Pro-延伸,1Pro-代换,和(或)C端Gly-Gly-Cys延伸获得的新型人GHRH类似肽活性有明显结构-功能关系:Pro-Pro-延伸<Pro-延伸<1Pro-代换;与标准的hGHRH(1-40)比较,1Pro-hGHRH(2-44)-GlyGly-Cys肽达到了相似的GH释放活性;其他垂体激素释放活性显示,6种新型类似肽均具有一定的垂体激素释放特异性。结论这种GHRH肽结构改构获得具有一定生物学活性的新类似肽,为未来深入研究结构-活性关系,打下良好的基础。

Objective To analyze the bioaetivity of six novel hGHRH analogs obtained by changing the N - terminal and/or C - terminal amino acid sequence of hGHRH （ 1 - 44 ）. Methods The six hGHRH analogs, including Pro - Pro - hGHRH（ 1 - 44 ）, Pro - hGHRH （ 1 - 44 ）,^ 1 Pro - GHRH （ 2 - 44 ）, Pro - Pro - hGHRH （ 1 - 44 ） - Gly - Gly - Cys, Pro - hGHRH （ 1 - 44 ） - Gly - Gly - Cys and ^1 Pro - GHRH （ 2 - 44） - Gly - Gly - Cys, were synthesized in solid phase with polypeptide synthesis technique. The purities and molecular weights of these peptides were determined by C18 RP- HPLC method and EIS- MS technique, respectively. The analogs- induced rat pituitary GH, PRL, LH, and ACTH releasing values were determined by ELISA kits. Results The modulated hGHRH analogs possessed GH releasing activities with structure - function dependent correlation, presenting Pro - Pro - hGHRH （ 1 - 44 ） 〈 Pro - hGHRH （ 1 - 44 ） 〈 ^1 Pro - GHRH （ 2 - 44 ）, Pro - Pro - hGHRH （ 1 - 44 ） - Gly - Gly - Cys 〈 Pro - hGHRH （ 1 - 44 ） - Gly - Gly - Cys 〈 ^1 Pro - GHRH （2 -44 ） - Gly - Gly - Cys. The latter peptide had similar activity with the standard hGHRH （ 1 -40 ）. Higher GH releasing activities were observed in the peptides with C - terminal Gly - Gly - Cys extension comparing with those without Gly - Gly - Cys extension. Specific GH releasing activity was revealed in these constructed GHRH analogs according to pituitary PRL, LH, and ACTH releasing results. Conclusion The N - terminal Pro modulations and/or C - terminal Gly- Gly- Cys extension regulate GH release in rats, providing a useful platform for further basic and clinical study.