科研之友
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摘要
We investigated the ability of type I collagen telopeptides to bind neighboring collagen molecules, which is thought to be the initial event in fibrillogenesis. Limited hydrolysis by actinidain protease produced monomeric collagen, which consisted almost entirely of alpha 1 and alpha 2 chains. As seen with ultrahigh resolution scanning electron microscopy, actinidain-hydrolyzed collagen exhibited unique self-assembly, as if at an intermediate stage, and formed a novel suprastructure characterized by poor fibrillogenesis. Then, the N- and C-terminal sequences of chicken type I collagen hydrolyzed by actinidain or pepsin were determined by Edman degradation and de novo sequence analysis with matrix-assisted laser desorption ionization-tandem time-of-flight mass spectrometry, respectively. In the C-telopeptide region of the alpha 1 chain, pepsin cleaved between Asp(1035) and Phe(1036), and actinidain between Gly(1032) and Gly(1033). Thus, the actinidain-hydrolyzed alpha 1 chain is shorter at the C terminus by three residues, Gly(1033), Phe(1034), and Asp(1035). In the alpha 2 chain, both proteases cleaved between Glu(1030) and Val(1031). We demonstrated that a synthetic nonapeptide mimicking the alpha 1 C-terminal sequence including GFD weakly inhibited the self-assembly of pepsin-hydrolyzed collagen, whereas it remarkably accelerated that of actinidain-hydrolyzed collagen. We conclude that the specific GFD sequence of the C-telopeptide of the alpha 1 chain plays a crucial role in stipulating collagen suprastructure and in subsequent fibril formation.
- 出版日期2010-6-4
