Ramshaw J A, Shah N K, Brodsky B
CSIRO Division of Molecular Science, Parkville, Victoria, 3052, Australia.
J Struct Biol. 1998;122(1-2):86-91. doi: 10.1006/jsbi.1998.3977.
The collagen triple-helix consists of a repeating (Gly-X-Y)n sequence. In theory, there are more than 400 possible Gly-X-Y triplets, but analysis of sequences from fibrillar and nonfibrillar collagens shows that only a limited set of triplets are found in significant numbers, and many are never observed. The nonrandom frequency of Gly-X-Y triplets makes it practical to experimentally approach the stability of much of the collagen sequence through the study of a limited set of host-guest peptides. In these peptides, individual Gly-X-Y triplets constitute the guest, while the host consists of Gly-Pro-Hyp tripeptides. A set of host-guest peptides was designed to contain the most common nonpolar and charged triplets found in collagen. All formed stable triple-helices, with their melting temperature depending on the identity of the guest triplet. While including less than 10% of all possible triplets, the data set covers 50-60% of collagen sequences and provides a starting point for establishing a stability scale to predict the relative stability of important collagen regions, such as the matrix metalloproteinase cleavage site or binding sites.
胶原蛋白三螺旋由重复的(Gly-X-Y)n序列组成。理论上，有400多种可能的Gly-X-Y三联体，但对纤维状和非纤维状胶原蛋白序列的分析表明，只有有限的一组三联体数量可观，许多三联体从未被观察到。Gly-X-Y三联体的非随机频率使得通过研究一组有限的主客体肽来实验性地研究大部分胶原蛋白序列的稳定性成为可能。在这些肽中，单个的Gly-X-Y三联体构成客体，而主体由Gly-Pro-Hyp三肽组成。设计了一组主客体肽，使其包含胶原蛋白中最常见的非极性和带电荷的三联体。所有这些肽都形成了稳定的三螺旋结构，其解链温度取决于客体三联体的特性。虽然该数据集包含的三联体不到所有可能三联体的10%，但却覆盖了50-60%的胶原蛋白序列，并为建立一个稳定性量表提供了起点，以预测重要胶原蛋白区域（如基质金属蛋白酶切割位点或结合位点）的相对稳定性。
