Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil.
J Pept Sci. 2012 Sep;18(9):588-98. doi: 10.1002/psc.2439. Epub 2012 Aug 2.
Gomesin (Gm) was the first antimicrobial peptide (AMP) isolated from the hemocytes of a spider, the Brazilian mygalomorph Acanthoscurria gomesiana. We have been studying the properties of this interesting AMP, which also displays anticancer, antimalarial, anticryptococcal and anti-Leishmania activities. In the present study, the total syntheses of backbone-cyclized analogues of Gm (two disulfide bonds), [Cys(Acm)(2,15)]-Gm (one disulfide bond) and [Thr(2,6,11,15),(D)-Pro(9)]-Gm (no disulfide bonds) were accomplished, and the impact of cyclization on their properties was examined. The consequence of simultaneous deletion of pGlu(1) and Arg(16) -Glu-Arg(18) -NH(2) on Gm antimicrobial activity and structure was also analyzed. The results obtained showed that the synthetic route that includes peptide backbone cyclization on resin was advantageous and that a combination of 20% DMSO/NMP, EDC/HOBt, 60 °C and conventional heating appears to be particularly suitable for backbone cyclization of bioactive peptides. The biological properties of the Gm analogues clearly revealed that the N-terminal amino acid pGlu(1) and the amidated C-terminal tripeptide Arg(16) -Glu-Arg(18) -NH(2) play a major role in the interaction of Gm with the target membranes. Moreover, backbone cyclization practically did not affect the stability of the peptides in human serum; it also did not affect or enhanced hemolytic activity, but induced selectivity and, in some cases, discrete enhancements of antimicrobial activity and salt tolerance. Because of its high therapeutic index, easy synthesis and lower cost, the [Thr(2,6,11,15),(D)-Pro(9)]-Gm analogue remains the best active Gm-derived AMP developed so far; nevertheless, its elevated instability in human serum may limit its therapeutic potential.
Gomesin (Gm) 是从巴西狼蛛的血细胞中分离出的第一种抗菌肽 (AMP)。我们一直在研究这种有趣的 AMP 的特性，它还具有抗癌、抗疟、抗隐球菌和抗利什曼原虫的活性。在本研究中，完成了 Gm（两个二硫键）、[Cys(Acm)(2,15)]-Gm（一个二硫键）和 [Thr(2,6,11,15),(D)-Pro(9)]-Gm（无二硫键）的骨干环化类似物的全合成，并研究了环化对其性质的影响。还分析了同时删除 pGlu(1) 和 Arg(16)-Glu-Arg(18)-NH(2) 对 Gm 抗菌活性和结构的影响。结果表明，包括在树脂上肽骨干环化的合成路线是有利的，并且 20% DMSO/NMP、EDC/HOBt、60°C 和常规加热的组合似乎特别适合生物活性肽的骨干环化。Gm 类似物的生物学特性清楚地表明，N 端氨基酸 pGlu(1) 和酰胺化的 C 端三肽 Arg(16)-Glu-Arg(18)-NH(2) 在 Gm 与靶膜相互作用中起主要作用。此外，骨干环化实际上不会影响肽在人血清中的稳定性；它也不会影响或增强溶血活性，但诱导选择性，在某些情况下，还会增强抗菌活性和耐盐性。由于其治疗指数高、合成简单、成本低，[Thr(2,6,11,15),(D)-Pro(9)]-Gm 类似物仍然是迄今为止开发的最有效的 Gm 衍生 AMP；然而，其在人血清中的不稳定性增加可能会限制其治疗潜力。
