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此前,我们曾报道过一种新的蛇毒肽(缓激肽加强肽,缩写为BIP),其在离体豚鼠回肠和大鼠胃底肌条上表现了不同的生理活性。为了探索它与其它缓激肽增强肽在生物活性上不同的原因,本文运用2D NMR技术研究了其在水溶液中的构象,利用RMSD和Ramachandran plot分析结果的可靠性。结果表明,Pro2、Pro3、Pro6和Pro10的肽键都处于反式构象,整体结构呈现“双S”形状,N-端(Pro2Pro3Ala4)形成新生螺旋,C-端(Asp7Val8Gly9Pro10)形成Ⅱ型β-转角。与其它缓激肽抑制剂(如HOE140)相比较,C-端的Ⅱ型β-转角在维持缓激肽抑制活性方面起到关键作用;而N端的新生螺旋结构可能与缓激肽加强活性有关。
Earlier, we reported a new snake venom peptide (bradykinin-potentiating peptide, abbreviated as BIP) that exhibits different physiological activities on guinea pig ileum and rat gastric fundus. In order to explore its biological activity with other bradykinin enhancer peptide, this paper uses 2D NMR technology to study its conformation in aqueous solution, using RMSD and Ramachandran plot to analyze the reliability of the results. The results showed that the peptide bonds of Pro2, Pro3, Pro6 and Pro10 were in trans conformation, the overall structure was “double S” shape, N-terminal (Pro2Pro3Ala4) formed a newborn spiral, C-terminal (Asp7Val8Gly9Pro10) - corner. Compared with other bradykinin inhibitors (such as HOE140), the C-terminal type Ⅱ β-turn plays a key role in maintaining the bradykinin inhibitory activity; whereas the N-terminal nascent helical structure may be related to bradykinin boosting activity.