Plants and their seeds have been shown to be a rich source of cystine-stabilized peptides. Recently a new family of plant seed peptides whose sequences are buried within precursors for seed storage vicilins was identified. Members of this Vicilin Buried Peptide (VBP) family are found in distantly related plant species including the monocot date palm, as well as dicotyledonous species like pumpkin and sesame. Genetic evidence for their widespread occurrence indicates that they are of ancient origin. Limited structural studies have been conducted on VBP family members, but two members have been shown to adopt a helical hairpin fold. We here present an extensive characterization of VBPs using solution NMR spectroscopy, to better understand their structural features. Four peptides were produced by solid phase peptide synthesis and shown to adopt a helix-loop-helix hairpin fold, as a result of the I-IV/II-III ladder-like connectivity of their disulfide bonds. Inter-helix interactions, including hydrophobic contacts and salt bridges, are critical for the fold stability and control the angle at which the anti-parallel α-helices interface. Activities reported for VBPs include trypsin inhibitory activity and inhibition of ribosomal function, however their diverse structural features despite a common fold suggest additional bioactivities yet to be revealed are likely.

中文翻译：

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定义纤溶酶埋肽家族的家族性折叠

已经证明植物及其种子是胱氨酸稳定肽的丰富来源。最近，发现了一个新的植物种子肽家族，其序列被埋在种子储存豌豆球蛋白的前体中。Vicilin埋藏肽（VBP）家族的成员存在于远缘相关的植物物种中，包括单子叶枣椰树以及双子叶植物，如南瓜和芝麻。它们广泛发生的遗传证据表明它们是古老的。对VBP家族成员进行了有限的结构研究，但已证明有两个成员采用螺旋发夹折叠。我们在这里提供了使用溶液NMR光谱对VBP的广泛表征，以更好地了解其结构特征。通过固相肽合成产生了四种肽，由于它们的二硫键具有I-IV / II-III阶梯状连接性，因此显示出采用螺旋-环-螺旋发夹折叠。螺旋间相互作用，包括疏水性接触和盐桥，对于折叠稳定性和控制反平行α-螺旋界面的角度至关重要。据报道，VBPs的活性包括胰蛋白酶抑制活性和核糖体功能抑制，尽管它们具有共同的折叠性，但其多样化的结构特征表明可能还有待进一步揭示的生物活性。对于折叠稳定性和控制反平行α螺旋界面的角度至关重要。据报道，VBPs的活性包括胰蛋白酶抑制活性和核糖体功能抑制，尽管它们具有共同的折叠性，但其多样化的结构特征表明可能还有待进一步揭示的生物活性。对于折叠稳定性和控制反平行α螺旋界面的角度至关重要。据报道，VBPs的活性包括胰蛋白酶抑制活性和核糖体功能抑制，尽管它们具有共同的折叠性，但其多样化的结构特征表明可能还有待进一步揭示的生物活性。