Veelaert D, Devreese B, Vanden Broeck J, Yu C G, Schoofs L, Van Beeumen J, Tobe S S, De Loof A
Zoological Institute, Katholieke Universiteit Leuven, Belgium.
Regul Pept. 1996 Dec 17;67(3):195-9. doi: 10.1016/s0167-0115(96)00131-0.
An octapeptide was isolated from 7000 brains of the desert locust. Schistocerca gregaria by screening of HPLC fractions using a RIA for Dip-AST-2 (allatostatin-2 from the cockroach). Maldi-TOF-MS revealed a mass of 921.4 Da. The primary structure of the peptide is LPVYNFGL-NH2. It is identical to the C-terminal portion of schistostatin-2 from Schistocerca gregaria. Therefore, it was designated Scg-AST-2(11-18). The chromatographic properties of the synthetic peptide are identical to these of the native peptide. The peptide is a truncated product of Scg-AST-2, suggesting that an endopeptidase which cleaves between Arg and Leu is present in the brain complex of S. gregaria. Although, Scg-AST-2(11-18) contains the same C-terminus as Dip-AST-2, it has no inhibitory activity on the corpora allata (CA) of 2-day-old virgin females of D. punctata. This suggests that Scg-AST2 (11-18) may be the result of a proteolytic inactivation mechanism and/or that it may be involved in stage-dependent down regulation of allatostatic activity. To our knowledge, Scg-AST-2 is the first isolated peptide which has the active core of the allatostatin peptide family but nevertheless shows no activity in this bioassay.
通过使用针对 Dip-AST-2（蟑螂的咽侧体抑制素-2）的放射免疫分析筛选高效液相色谱馏分，从 7000 只沙漠蝗虫（飞蝗）的脑中分离出一种八肽。基质辅助激光解吸电离飞行时间质谱（Maldi-TOF-MS）显示其分子量为 921.4 Da。该肽的一级结构为 LPVYNFGL-NH2。它与飞蝗的血吸虫抑制素-2 的 C 末端部分相同。因此，它被命名为 Scg-AST-2(11-18)。合成肽的色谱性质与天然肽相同。该肽是 Scg-AST-2 的截短产物，表明在飞蝗的脑复合体中存在一种在 Arg 和 Leu 之间切割的内肽酶。尽管 Scg-AST-2(11-18)与 Dip-AST-2 含有相同的 C 末端，但它对 2 日龄未交配的斑点黑蝗雌性的咽侧体（CA）没有抑制活性。这表明 Scg-AST2 (11-18)可能是蛋白水解失活机制的结果和/或它可能参与了咽侧体抑制活性的阶段依赖性下调。据我们所知，Scg-AST-2 是第一个分离出的具有咽侧体抑制素肽家族活性核心但在该生物测定中却无活性的肽。
