Rede Nordeste de Biotecnologia-RENORBIO, Universidade Estadual do Ceará, Campus do Itaperi, CEP: 60714-903 Fortaleza, CE, Brazil; Laboratório de Bioquímica, Embrapa Caprinos e Ovinos, Estrada Sobral-Groaíras, Km 4, CP 71, CEP: 62010-970 Sobral, CE, Brazil.
Laboratório de Bioquímica, Embrapa Caprinos e Ovinos, Estrada Sobral-Groaíras, Km 4, CP 71, CEP: 62010-970 Sobral, CE, Brazil.
J Proteomics. 2020 Apr 15;217:103692. doi: 10.1016/j.jprot.2020.103692. Epub 2020 Feb 14.
Cationic peptides found in Moringa oleifera seeds belong to different protein families and are described as the main flocculating agents of the species. In this study we report the identification and isolation of four new flocculant peptides, called Mo-HLPs 1-4, belonging to the family of hevein-like peptides, previously only known for their members' antimicrobial activity. Purification of the peptides followed two sequential membrane ultrafiltration steps and separation by reverse-phase liquid chromatography. Proteomic analyses showed that Mo-HLPs are extremely basic (pI >10) cysteine-rich molecules with molecular masses between 4.5 and 4.8 kDa and with a highly conserved chitin-binding domain. Searches in BLAST revealed high similarity of Mo-HLPs with hevein and other hevein-like peptides and 90% identity with morintides, which are members of the 8C-hevein-like subfamily found in M. oleifera leaves. Mo-HLPs microflocculation assays showed distinct coagulation/flocculation efficiencies, promoting turbidity reduction levels between 67 and 89% in synthetic turbid water. Activity variations were attributed to the substitution of some amino acids among the isoforms, which may have altered the final net charge of the molecules. The identification of Mo-HLPs represents the discovery of a new group of cationic peptides involved in the flocculation properties of M. oleifera seeds. SIGNIFICANCE: The study reveals the presence of hevein-like peptides in Moringa oleifera seeds. It is reported for the first time that members of this family have properties to act as flocculating agents of importance for water treatment processes. The identification of these peptides as well as new functional assignment broadens the horizon for speculation on new species which could act as sources of green coagulants for sustainable water treatment, and contributes to the knowledge about occurrence, distribution, molecular and active diversity of peptides belonging to the hevein-like family.
辣木种子中发现的阳离子肽属于不同的蛋白质家族，被描述为该物种的主要絮凝剂。在这项研究中，我们报告了四种新的絮凝肽的鉴定和分离，称为 Mo-HLPs 1-4，属于 hevein 样肽家族，以前仅因其成员的抗菌活性而被知晓。肽的纯化遵循两个连续的膜超滤步骤和反相液相色谱分离。蛋白质组学分析表明，Mo-HLPs 是非常碱性（pI>10）的富含半胱氨酸的分子，分子量在 4.5 到 4.8 kDa 之间，具有高度保守的几丁质结合结构域。BLAST 搜索显示 Mo-HLPs 与 hevein 和其他 hevein 样肽具有高度相似性，与 morintides 的同源性为 90%，morintides 是在辣木叶片中发现的 8C-hevein 样亚家族的成员。Mo-HLPs 的微絮凝实验显示出明显的混凝/絮凝效率，在合成浊度水中促进浊度降低水平在 67%到 89%之间。活性变化归因于同工型中一些氨基酸的取代，这可能改变了分子的最终净电荷。Mo-HLPs 的鉴定代表了发现了一组新的参与辣木种子絮凝特性的阳离子肽。意义：该研究揭示了辣木种子中存在 hevein 样肽。据报道，该家族的成员具有作为水处理过程中絮凝剂的重要性质，这是首次报道。这些肽的鉴定以及新的功能分配拓宽了对新物种的推测范围，这些新物种可能成为可持续水处理的绿色凝结剂的来源，并为属于 hevein 样家族的肽的存在、分布、分子和活性多样性的知识做出了贡献。
