Long C G, Braswell E, Zhu D, Apigo J, Baum J, Brodsky B
Department of Biochemistry, UMDNJ-Robert Wood Johnson Medical School, Piscataway 08854.
Biochemistry. 1993 Nov 2;32(43):11688-95. doi: 10.1021/bi00094a027.
Glycine is found as every third residue along the entire length of triple helices in fibrillar collagens, but the triple-helix regions of nonfibrillar collagens and other proteins usually contain one or more interruptions in this repeating pattern. A set of four peptides was designed to model the effect of interruptions in the (Gly-X-Y)n repeating pattern on triple-helix formation, stability, and folding. Into the middle of the stable triple-helical peptide (Pro-Hyp-Gly)10, an interruption was introduced representing one of the four possible categories: a glycine deletion, a deletion of a hydroxyproline (Y position), an alanine insertion, or a glycine to alanine substitution. As shown by sedimentation equilibrium, NMR, and CD studies, the introduction of an interruption still allowed formation of trimers in solution, but with marked decrease in stability. The degree of destabilization and the thermodynamic basis for the loss of stability depended on the type of interruption. The glycine substitution and alanine insertion were the least disruptive, followed by the hydroxyproline deletion, with the glycine deletion being the most destabilizing. Our results suggest that the breaks in these peptides affect both the triple-helical conformation and the monomer conformation. These studies provide a basis for considering the structural and functional consequences of different kinds of interruptions in collagen.
在纤维状胶原蛋白的三股螺旋全长中，每隔两个残基就会出现甘氨酸，但非纤维状胶原蛋白和其他蛋白质的三股螺旋区域在这种重复模式中通常含有一个或多个中断。设计了一组四个肽来模拟（Gly-X-Y）n重复模式中的中断对三股螺旋形成、稳定性和折叠的影响。在稳定的三股螺旋肽（Pro-Hyp-Gly）10中间引入了一个中断，代表四种可能类型之一：甘氨酸缺失、羟脯氨酸（Y位）缺失、丙氨酸插入或甘氨酸到丙氨酸的取代。沉降平衡、核磁共振和圆二色性研究表明，引入中断仍能使三聚体在溶液中形成，但稳定性显著降低。去稳定程度和稳定性丧失的热力学基础取决于中断的类型。甘氨酸取代和丙氨酸插入的干扰最小，其次是羟脯氨酸缺失，甘氨酸缺失的去稳定作用最大。我们的结果表明，这些肽中的中断会影响三股螺旋构象和单体构象。这些研究为考虑胶原蛋白中不同类型中断的结构和功能后果提供了基础。
