Author
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Kronick, Paul |
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Cooke, Peter |
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Submitted to: Protein Structure or General Subjects
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/1/1995 Publication Date: N/A Citation: N/A Interpretive Summary: Leather is tanned by linking the collagen protein molecules of hide to one another to make them more stable. The most common crosslinker has been chromium oxides, but replacements are being sought in order to reduce dependency on this heavy metal. Collagen molecules are composed of about 11 domains that melt independently of each other, so stability depends on how crosslinks react with all domains. By directly observing crystals with molecules packed side-by-side, we find that crosslinking does not affect particular domains preferentially. Novel tanning reagents should be developed that will react with all parts of the collagen molecule, since the chemistry of individual domains does not control the stability. Technical Abstract: Type-I collagen appears to melt as a collection of at least 11 domains, rather than in a simple two-state process. Minimal crosslinking with glutaraldehyde raises the melting point of monomeric collagen by about 35 C. The monophasic endotherm shows no evidence for a preferred domain for crosslinking. In the segment-long-spacing (SLS) form native collagen melts at 46 C, about the same temperature as does reconstituted staggered-molecule fibrils. Although the melting range is 4-8 C, double that of monomeric collagen, direct observation in an electron microscope did not show partial melting by domains. When crosslinked with glutaraldehyde, the melting point was raised to 65 C and the melting range increased to 20 C. There was again no evidence for selectively crosslinked domains. Domain melting seems to have no practical effect on the stability of collagen except for the size of the melting range, by which its existence was deduced. |
