| Collagen is the most abundant protein in animals existing as the predominant component of the extracellular matrix. Collagens not only maintain structural integrity of tissues and organs, but also regulate a number of biological events, including cell attachment, differentiation, tissue regeneration and animal development. Collagens are characterized by their unique tertiary structure, called the collagen triple helix, which is always a subject of hot debate in protein research. Despite their importance it is very difficult to study the biochemistry of natural collagens because of its insolubility and the inherent heterogeneity, collagen model peptides have been designed and are used as collagen surrogates in studies on collagen structure, stability, folding and biological functions. Molecular marker has also been widely used in biochemistry, but poorly been utilize in collagen triple helix. We designed a host-guest model peptide contained only one 4-aminoproline flanked by several repeats of Gly-Pro-Hyp triplet. Many labeled peptides were synthetized based on the reaction between free amino of model peptide and carboxyl of labeled molecule, such as fluorescein, free radical of nitroxide and galactopyranose acid. Then the model peptide and labeled peptides were analyzed by EPR spectra, fluorescence spectra and CD spectra. Unfolding of the labeled peptide triple helices caused the phenomena of increasing fluorescence and paramagnetic resonance intensity early but decreasing late. And collagen model glycopeptide with C-linked glycosidic bond increased stability of triple helix. In conclusion, the collagen labeled peptides described here is useful for stabilizing and probing the collagenous triple helix as well as to research triple helix formation. This peptides system opens new opportunities for studies on collagen folding, structure, and biochemistry, as well as guiding further development of artificial collagenous materials for biomedicine and nanotechnology. |
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