School of Life and Environmental Sciences and the Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW, Australia.
School of Chemistry, University of Sydney, Sydney, NSW, Australia.
Antimicrob Agents Chemother. 2020 Sep 21;64(10). doi: 10.1128/AAC.00842-20.
Lactoferrin (LF) is an iron-binding glycoprotein with broad-spectrum antimicrobial activity. Previously, we discovered that LF synergistically enhanced the antifungal efficacy of amphotericin B (AMB) across a variety of yeast species and subsequently hypothesized that this synergy was enhanced by the presence of small peptides derived from the whole LF molecule. In this study, LF was digested with pepsin under a range of conditions. The resulting hydrolysates exhibited enhanced synergy with AMB compared to its synergy with undigested LF. Samples were analyzed using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, and 14 peptides were identified. The sequences of these peptides were predicted by matching their molecular weights to those of a virtual digest with pepsin. The relative intensities of predicted peptides in each hydrolysate were compared with the activity of the hydrolysate, and the structural and physicochemical properties of the peptides were assessed. From this, a 30-residue peptide was selected for synthesis and dubbed lactofungin (LFG). Pure LFG was highly synergistic with AMB, outperforming native LF in all fungal species tested. With potential for further structural and chemical improvements, LFG is an excellent lead for development as an antifungal adjuvant.
乳铁蛋白（LF）是一种具有广谱抗菌活性的铁结合糖蛋白。此前，我们发现 LF 与两性霉素 B（AMB）协同作用，增强了多种酵母物种的抗真菌疗效，随后假设这种协同作用是由 LF 整个分子衍生的小肽的存在增强的。在这项研究中，LF 在一系列条件下用胃蛋白酶消化。与未消化的 LF 相比，所得水解产物与 AMB 的协同作用增强。使用基质辅助激光解吸电离飞行时间（MALDI-TOF）质谱法对样品进行分析，鉴定出 14 种肽。通过将这些肽的分子量与胃蛋白酶虚拟消化产物进行匹配来预测这些肽的序列。将每个水解产物中预测肽的相对强度与水解产物的活性进行比较，并评估肽的结构和物理化学性质。由此，选择一个 30 个残基的肽进行合成，并命名为乳铁真菌素（LFG）。纯 LFG 与 AMB 高度协同，在所有测试的真菌物种中均优于天然 LF。由于具有进一步的结构和化学改进的潜力，LFG 是作为抗真菌佐剂开发的极佳先导。
