Department of Pediatrics, Eastern Virginia Medical School, Norfolk, VA, United States of America.
Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA, United States of America.
PLoS One. 2019 Dec 31;14(12):e0226875. doi: 10.1371/journal.pone.0226875. eCollection 2019.
A product of rational molecular design, PA-dPEG24 is the lead derivative of the PIC1 family of peptides with multiple functional abilities including classical complement pathway inhibition, myeloperoxidase inhibition, NET inhibition and antioxidant activity. PA-dPEG24 is composed of a sequence of 15 amino acid, IALILEPICCQERAA, and contains a monodisperse 24-mer PEGylated moiety at its C terminus to increase aqueous solubility. Here we explore a sarcosine substitution scan of the PA peptide to evaluate impacts on solubility in the absence of PEGylation and functional characteristics.
Sixteen sarcosine substitution variants were synthesized and evaluated for solubility in water. Aqueous soluble variants were then tested in standard complement, myeloperoxidase, NET formation and antioxidant capacity assays.
Six sarcosine substitution variants were aqueous soluble without requiring PEGylation. Substitution with sarcosine of the isoleucine at position eight yielded a soluble peptide that surpassed the parent molecule for complement inhibition and myeloperoxidase inhibition. Substitution with sarcosine of the cysteine at position nine improved solubility, but did not otherwise change the functional characteristics compared with the parent compound. However, replacement of both vicinal cysteine residues at positions 9 and 10 with a single sarcosine residue reduced functional activity in most of the assays tested.
Several of the sarcosine PIC1 variant substitutions synthesized yielded improved solubility as well as a number of unanticipated structure-function findings that provide new insights. Several sarcosine substitution variants demonstrate increased potency over the parent peptide suggesting enhanced therapeutic potential for inflammatory disease processes involving complement, myeloperoxidase, NETs or oxidant stress.
PA-dPEG24 是 PIC1 肽家族的先导衍生物,是理性分子设计的产物,具有多种功能能力,包括经典补体途径抑制、髓过氧化物酶抑制、NET 抑制和抗氧化活性。PA-dPEG24 由 15 个氨基酸组成,IALILEPICCQERAA,其 C 末端含有单分散的 24 聚乙二醇化部分,以增加水溶性。在这里,我们探索了 PA 肽的肌氨酸取代扫描,以评估在没有聚乙二醇化的情况下对溶解度的影响和功能特性。
合成了 16 种肌氨酸取代变体,并评估了它们在水中的溶解度。然后在标准补体、髓过氧化物酶、NET 形成和抗氧化能力测定中测试了水溶性变体。
6 种肌氨酸取代变体在不需要聚乙二醇化的情况下是水溶性的。用 8 位异亮氨酸取代肌氨酸得到一种可溶性肽,其对补体抑制和髓过氧化物酶抑制的作用超过了母体分子。用 9 位半胱氨酸取代肌氨酸提高了溶解度,但与母体化合物相比,其他功能特性没有改变。然而,用单个肌氨酸取代 9 位和 10 位的两个相邻半胱氨酸残基,在大多数测试的测定中降低了功能活性。
合成的几种肌氨酸 PIC1 变体取代物提高了溶解度,同时也发现了一些意想不到的结构-功能关系,提供了新的见解。几种肌氨酸取代变体的效力超过了母体肽,这表明在涉及补体、髓过氧化物酶、NET 或氧化应激的炎症性疾病过程中具有增强的治疗潜力。