Siriwardena Thissa N, Gan Bee-Ha, Köhler Thilo, van Delden Christian, Javor Sacha, Reymond Jean-Louis
Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.
Department of Microbiology and Molecular Medicine, University of Geneva, Service of Infectious Diseases, University Hospital of Geneva, 1211 Geneva, Switzerland.
ACS Cent Sci. 2021 Jan 27;7(1):126-134. doi: 10.1021/acscentsci.0c01135. Epub 2021 Jan 19.
Solid-phase peptide synthesis (SPPS) is usually performed with optically pure building blocks to prepare peptides as single enantiomers. Herein we report that SPPS using racemic amino acids provides stereorandomized () peptides, containing up to billions of different stereoisomers, as well-defined single HPLC peaks, single mass products with high yield, which can be used to investigate peptide bioactivity. To exemplify our method, we show that stereorandomization abolishes the membrane-disruptive effect of α-helical amphiphilic antimicrobial peptides but preserves their antibiofilm effect, implying different mechanisms involving folded versus disordered conformations. For antimicrobial peptide dendrimers by contrast, stereorandomization preserves antibacterial, membrane-disruptive, and antibiofilm effects but reduces hemolysis and cytotoxicity, thereby increasing their therapeutic index. Finally, we identify partially stereorandomized analogues of the last resort cyclic peptide antibiotic polymyxin B with preserved antibacterial activity but lacking membrane-disruptive and lipopolysaccharide-neutralizing activity, pointing to the existence of additional targets.
固相肽合成（SPPS）通常使用光学纯的构建模块来制备单一对映体的肽。在此我们报告，使用外消旋氨基酸的SPPS可提供立体随机化的（）肽，其包含多达数十亿种不同的立体异构体，作为明确的单一HPLC峰、高产率的单一质量产物，可用于研究肽的生物活性。为了举例说明我们的方法，我们表明立体随机化消除了α-螺旋两亲抗菌肽的膜破坏作用，但保留了它们的抗生物膜作用，这意味着涉及折叠与无序构象的不同机制。相比之下，对于抗菌肽树枝状大分子，立体随机化保留了抗菌、膜破坏和抗生物膜作用，但降低了溶血和细胞毒性，从而提高了它们的治疗指数。最后，我们鉴定出了最后手段环状肽抗生素多粘菌素B的部分立体随机化类似物，其保留了抗菌活性，但缺乏膜破坏和脂多糖中和活性，这表明存在其他靶点。
