We extend our study of the structural stability of helical and nonhelical regions in chain A of human intelectin-1 to include a second human intelectin (4WMY) and the frog protein “Xenopus embryonic epidermal lectin” (XEEL). These unique lectins have been shown to recognize carbohydrate residues found exclusively in microbes, thus they could potentially be developed into novel microbe detection and sequestration tools. We believe that by studying the structural stability of these proteins we can provide insights on their biological role and activities. Using a geometrical model introduced previously, we perform computational analyses of protein crystal structures that quantify the resiliency of the native state to steric perturbations. Based on these analyses, we conclude that differences in the resiliency of the human and frog proteins can be attributed primarily to differences in non-helical regions and to residues near Ca ions. Since these differences are particularly pronounced in the vicinity of the ligand binding site, they provide an explanation for the finding that human intelectin-1 has a higher affinity for a ligand than XEEL. We also present data on conserved and position-equivalent pairs of residues in 4WMY and XEEL. We identify residue pairs as well as regions in which the influence of neighboring residues is nearly uniform as the parent protein denatures. Since the structural signatures are conserved, this identification provides a basis for understanding why both proteins exhibit trimeric structures despite poor sequence conservation at the interface.

我们扩展了对人类intelectin-1链A的螺旋和非螺旋区域的结构稳定性的研究，以包括第二种人类intelectin（4WMY）和青蛙蛋白“非洲爪蟾胚胎表皮凝集素”（XEEL）。这些独特的凝集素已被证明可以识别仅存在于微生物中的碳水化合物残基，因此它们有可能被开发为新型的微生物检测和螯合工具。我们相信，通过研究这些蛋白质的结构稳定性，我们可以提供有关其生物学作用和活性的见解。使用先前介绍的几何模型，我们对蛋白质晶体结构进行了计算分析，从而量化了自然状态对空间扰动的适应性。根据这些分析，我们得出的结论是，人类和青蛙蛋白的回弹力差异可能主要归因于非螺旋区域的差异以及Ca离子附近的残基。由于这些差异在配体结合位点附近特别明显，因此它们为以下发现提供了解释：人intelectin-1对配体的亲和力比XEEL高。我们还提出了在4WMY和XEEL中的保守和位置等效残基对的数据。我们确定残基对以及其中相邻残基的影响几乎一样作为母体蛋白质变性的区域。由于结构特征是保守的，因此该鉴定为理解为何尽管界面处的序列保守性差但两种蛋白质仍显示三聚体结构提供了基础。