Department of Microbiology, Faculty of Science and Informatics, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary.
Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.
Molecules. 2018 Sep 1;23(9):2224. doi: 10.3390/molecules23092224.
Surfactins are cyclic lipopeptides consisting of a β-hydroxy fatty acid of various chain length and a peptide ring of seven amino acids linked together by a lactone bridge, forming the cyclic structure of the peptide chain. These compounds are produced mainly by species and possess numerous biological effects such as antimicrobial (antiviral, antibacterial, and antifungal) activities. A mixture of surfactins extracted from strain SZMC 6179J was examined by HPLC-ESI-IT-MS technique, enhancing their separation to reveal novel lipopeptide varieties with higher masses and to characterize their structures. During the MS² spectra analyses of their sodiated molecular ions [M + Na]⁺, a previously rarely encountered group of surfactins was detected and two novel types of the group were discovered containing methyl esterified aspartic acid residue in their fifth amino acid position. The relative amounts of these monomethyl isoforms exceeded 35% of the produced surfactin in total. In the / value of 1114, all the detected isoforms possessed aspartic acid 4-methyl ester residue in their fifth amino acid position (C17-[Lxx4, AME5], C18-[AME5]), offering an opportunity to separate a pure fraction of the compound and to study its biological activities in the future.
表面活性剂是由β-羟基脂肪酸和七氨基酸组成的环状脂肽，通过内酯桥连接形成环状肽链结构。这些化合物主要由 产生，具有多种生物效应，如抗菌（抗病毒、抗菌和抗真菌）活性。从 菌株 SZMC 6179J 中提取的表面活性剂混合物通过 HPLC-ESI-IT-MS 技术进行了检查，增强了它们的分离，揭示了具有更高质量的新型脂肽品种，并对其结构进行了表征。在它们的加钠离子[M + Na]⁺的 MS²光谱分析中，检测到了一组以前很少遇到的表面活性剂，发现了两种新型的含有第五个氨基酸位置甲酯化天冬氨酸残基的组。这些单甲基异构体的相对含量超过总产生的表面活性剂的 35%。在 / 值为 1114 时，所有检测到的异构体在第五个氨基酸位置（C17-[Lxx4，AME5]、C18-[AME5]）都具有天冬氨酸 4-甲酯残基，为分离该化合物的纯组分并研究其未来的生物活性提供了机会。
