STRUCTURAL STUDIES OF CONNECTIVE TISSUE

胶原蛋白在结缔组织疾病中的作用 巨噬细胞清道夫受体C1q的健康相关意义 和其他含有三螺旋的蛋白质使它变得重要 阐明三螺旋的性质。这个实验室已经使用了 确定序列的三螺旋多肽探讨其作用机制 构象上的氨基酸序列，我们的多肽提供了一个 为协作研究奠定基础，实现第一个高分辨率 三螺旋结构的X-射线结晶学研究及首次二维结构 三螺旋分子的核磁共振研究。要了解他们的倾向 不同残基采用三螺旋构象，一组 主客体多肽将被合成，其中单个“客体”Gly-X-Y 三肽单元被引入到Gly-Pro-Hyp的限定环境中 单位。最常见的Gly-X-Y三联体的相对稳定性将 被用于检测胶原蛋白序列的变异，并将被 与分子建模一起用来定义相互作用 稳定三螺旋结构。多肽的静电相互作用 用单甘氨酸-谷氨酸-赖氨酸单元进行了表征，晶体 获得的这种多肽将允许分子定义这些 互动。三肽的频率和聚集性分析 单位将在胶原蛋白和非胶原蛋白的三螺旋上完成 蛋白质，以阐明所有三螺旋的共同特征和特征 与特定的更高级别的交互有关。三螺旋结构域 与各种各样的配体相互作用，但几乎没有信息 关于构成特定基础的分子相互作用 识别沿相当均匀的三螺旋的位置。去探索 在认识的基础上，将开展重叠研究 含有胶原表位周围序列的多肽 单抗。设计实验是为了验证这一假设。 这种识别是通过行列式序列实现的 被含有Gly-Gly序列的柔性三联体包围。A肽 包含三螺旋配体结合区的序列 巨噬细胞清道夫受体的研究也将确定基础 由于其广泛而独特的多阴离子配体的特异性。甘氨酸 I型胶原蛋白三螺旋中的替代在许多 成骨不全(“脆性骨”病)的病例，但不是 明确不同的临床表型，从轻微到致命， 与取代物沿-链的位置有关。一颗甘油- 残基901位大于Ser突变导致轻度OI病例，但 残基913位的甘氨酸大于丝氨酸可导致致死性OI病例。 将合成多肽以阐明不同的局部 这些突变的环境是在 胶原蛋白稳定性和临床表型。这些研究将使 对理解蛋白质所需的基本相互作用的贡献 稳定性以及为审议以下事项建立结构基础 三螺旋结构和三螺旋结构域的抗体，在 病态。

The involvement of collagens in connective tissue diseases, together with the health related implications of the macrophage scavenger receptor, C1q and other triple-helix containing proteins makes it important to elucidate the properties of the triple-helix. This laboratory has used triple-helical peptides of defined sequence to approach the effect of amino acid sequence on conformation, and our peptides have provided a basis for collaborative studies leading to the first high resolution structure of a triple-helix by x-ray crystallography and the first 2-D NMR studies of triplehelica1 molecules. To understand the propensities of different residues to adopt a triple-helical conformation, a set of host-guest peptides will be synthesized where a single "guest" Gly-X-Y tripeptide unit is introduced into a defined environment of Gly-Pro-Hyp units. The relative stabilities of the most common Gly-X-Y triplets will be applied to detect variations along collagen sequences and will be used, together with molecular modeling, to define interactions stabilizing the triple-helix. The electrostatic interactions of a peptide with a single Gly-Glu-Lys unit have been characterized, and crystals obtained of this peptide will allow a molecular definition of these interactions. Analyses of the frequencies and clustering of tripeptide units will be done on triple-helices of collagens and non-collagenous proteins to clarify features common to all triple-helices and features related to specific higher level interactions. Triple-helical domains interact with a wide variety of ligands, yet there is little information on the molecular interactions which form the basis of specific recognition of sites along the rather uniform triple-helix. To explore the basis of recognition, studies will be carried out on overlapping peptides containing sequences surrounding a collagen epitope to a monoclonal antibody. Experiments are designed to -test the hypothesis that recognition is achieved by the determinant sequence when it is surrounded by flexible triplets containing Gly-Gly sequences. A peptide containing sequences of the triple-helical ligand binding region of the macrophage scavenger receptor will also be studied to determine the basis for its broad yet discriminating polyanionic ligand specificity. Glycine substitutions in type I collagen triple-helices have been found in many cases of osteogenesis imperfecta ("brittle bone" disease), but it is not clear how the variable clinical phenotypes, ranging from mild to lethal, relate to the location of the substitution along the-chain. A single Gly- greater than Ser mutation at residue 901 results in a mild OI case, yet a Gly- greater than Ser at residue 913 results in a lethal OI case. Peptides will be synthesized to clarify whether different local environments of these mutations are the cause of variations seen in collagen stability and clinical phenotype. These studies will make a contribution to understanding the basic interactions required for protein stability as well as developing a structural basis for consideration of the triple-helix, and antibodies to triple-helical domains, in pathological states.