Histatin 5 (Hst-5) is an antimicrobial peptide with strong antifungal activity against Candida albicans, an opportunistic pathogen that is a common cause of oral thrush. The peptide is natively secreted by human salivary glands and shows promise as an alternative therapeutic against infections caused by C. albicans. However, Hst-5 can be cleaved and inactivated by a family of secreted aspartic proteases (Saps) produced by C. albicans. Single-residue substitutions can significantly affect the proteolytic resistance of Hst-5 to Saps and its antifungal activity; the K17R substitution increases resistance to proteolysis, while the K11R substitution enhances antifungal activity. In this work, we showed that the positive effects of these two single-residue modifications can be combined in a single peptide, K11R-K17R, with improved proteolytic resistance and antifungal activity. We also investigated the effect of additional single-residue substitutions, with a focus on the effect of addition or removal of negatively charged residues, and found Sap-dependent effects on degradation. Both single- and double-substitutions affected the kinetics of proteolytic degradation of the intact peptide and of the fragments formed during degradation. Our results demonstrate the importance of considering proteolytic stability and not just antimicrobial activity when designing peptides for potential therapeutic applications.

中文翻译：

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组蛋白5修饰对抗真菌活性和蛋白水解动力学的影响。

Histatin 5（Hst-5）是一种抗菌肽，对白色念珠菌具有很强的抗真菌活性，白色念珠菌是一种机会致病菌，是导致鹅口疮的常见原因。该肽是人类唾液腺天然分泌的，并有望作为对抗白色念珠菌感染的替代疗法。但是，Hst-5可以被白色念珠菌产生的一系列分泌的天冬氨酸蛋白酶（Saps）裂解和失活。单残基取代可显着影响Hst-5对Saps的蛋白水解抗性及其抗真菌活性。K17R取代增加了对蛋白水解的抵抗力，而K11R取代则增强了抗真菌活性。在这项工作中，我们证明了这两个单残基修饰的积极作用可以结合在单个肽K11R-K17R中，具有改善的蛋白水解抗性和抗真菌活性。我们还研究了其他单残基取代的影响，重点是添加或去除带负电荷的残基的影响，并发现了Sap依赖于降解的影响。单取代和双取代都影响完整肽和在降解过程中形成的片段的蛋白水解降解的动力学。我们的结果表明，在设计潜在治疗应用的肽时，不仅要考虑蛋白水解的稳定性，而且要考虑抗菌活性。单取代和双取代都影响完整肽和降解过程中形成的片段的蛋白水解降解动力学。我们的结果表明，在设计潜在治疗应用的肽时，不仅要考虑蛋白水解的稳定性，而且要考虑抗菌活性。单取代和双取代都影响完整肽和在降解过程中形成的片段的蛋白水解降解的动力学。我们的结果表明，在设计潜在治疗应用的肽时，不仅要考虑蛋白水解的稳定性，而且要考虑抗菌活性。