Structural Studies of Triple-Helical Proteins

一种全面理解氨基酸序列效应的肽方法 （Gly-X-Y）n对正常和突变型胶原蛋白三螺旋的稳定性、构象、折叠、动力学和自缔合的研究正在进行中。我们的目标是在分子水平上完成序列稳定性相关性;开发肽来模拟三螺旋自缔合;并追求胶原蛋白疾病中发现的Gly取代引起的破坏。先前的主客体肽研究确定了X和Y位置的所有20个氨基酸的三螺旋倾向，并将完成三螺旋内分子相互作用的评价。Gly-X-Y序列和稳定性之间的这些关系将用于制定胶原蛋白模型肽的全局稳定性的预测，并将局部稳定性变化沿着胶原蛋白与配体结合位点、涉及原纤维形成的微去折叠和突变的临床严重性相关联。量热法的调查，提出了详细的三螺旋的羟脯氨酸稳定的机制，并提出进一步研究最近建立的序列相关的调制三螺旋扭曲。一个重要的目标是建立一个肽系统来模拟三螺旋的自缔合，因为胶原蛋白在超分子组装中起作用，并且一些胶原蛋白突变是病理性的，因为它们对更高级结构的影响。设计自缔合肽的策略将包括成对的带相反电荷的残基， 促进套准阵列和适应粘性末端和重复图案设计， 交错排列研究提出的肽模型的I型胶原蛋白突变导致骨疾病（成骨细胞）和VII型胶原蛋白突变导致皮肤起泡疾病（营养不良形式的大疱性表皮）。将检查突变的直接序列环境的影响和替换Gly的残基的同一性。通过肽研究将胶原蛋白的结构、动力学和折叠置于坚实的物理化学框架中，将为理解自缔合和结合的正常生物活性以及受这种丰富蛋白影响的许多疾病中发生的变化提供背景。

A peptide approach to a comprehensive understanding of the effect of amino acid sequence (Gly-X-Y)n on the stability, conformation, folding, dynamics and self-association of the normal and mutant collagen triple-helix is in progress. Our goals are to complete sequence-stability correlations at the molecular level; to develop peptides to model triple-helix self-association; and to pursue the disruption caused by Gly substitutions found in collagen diseases. Previous host-guest peptide studies established the triple-helix propensities of all 20 amino acids for the X and Y positions, and evaluation of molecular interactions within the triple-helix will be completed. These relationships between Gly-X-Y sequence and stability will be used to formulate predictions for the global stability of collagen model peptides and to relate local stability variations along collagen with ligand binding sites, microunfolding implicated in fibril formation, and the clinical severity of mutations. Calorimetric investigations are proposed to elaborate the mechanism of hydroxyproline stabilization of the triple-helix, and studies are proposed to further investigate the recently established sequence related modulation of triple-helix twist. An important goal is to establish a peptide system to model the self-association of triple-helices, since collagens function in supramolecular assemblies and some collagen mutations are pathological because of their influence on higher order structure. Strategies to design self-associating peptides will include pairs of oppositely charged residues to promote in register arrays and adaptation of sticky end and repeating pattern designs to form staggered arrays. Studies are proposed on peptide models of type I collagen mutations leading to a bone disease (osteogenesis imperfecta) and of type VII collagen mutations leading to a blistering skin disease (dystrophoic form of epidermolysis bullosa). The effect of the immediate sequence environment of the mutation and the identity of the residue replacing the Gly will be examined. Placing collagen structure, dynamics, and folding in a solid physicochemical framework through peptide studies will provide a context for understanding normal biological activities of selfassociation and binding, and for the changes occurring in many diseases affected by this abundant protein.