Collagen self-assembly

The ability of collagen molecules to assemble into crosslinked fibrils is an important requirement for the development of tissue strength. Although 

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Kadler K, Hojima Y, Prockop DJ (1987) Assembly of collagen fibrils de novo by cleavage of the type I pC-collagen with procollagen C-proteinase. Assay of critical concentration demonstrates that collagen self-assembly is a classical example of an entropy-driven process. J Biol Chem 262 15696-15701... 

Helseth, D. L., and Veis, A. (1981). Collagen self-assembly in vitro. Differentiating specific telopeptide dependent interactions using selective enzyme modification and the addition of free amino telopeptide./. Biol. Chem. 256, 7118-7128. 

Figure 5.3. Turbidity-time curve illustrating collagen self-assembly.Turbidity-time curve illustrating lag phase, during which small linear and lateral aggregates form, and growth phase, during which unit fibers form that rapidly grow into fibers. The plateau is characteristic of termination of fibril growth.

Figure 5.5. Measurement of physical properties during initiation of collagen self-assembly. Translation diffusion coefficient (D20-w) (top) and intensity of scattered light at 90° (bottom) versus time for type I collagen. Note translational diffusion constant decreases, whereas intensity of scattered light remains initially unchanged.

Figure 5.6. Collagen self-assembly. The diagram models the initiation of collagen self-assembly via formation of linear aggregates containing about three molecules that then laterally associate. The lateral assembly step may require a supramolecu-lar twist, explaining why linear aggregation precedes lateral aggregation.

Figure 5.7. Diagram showing role of N- and C-propeptides in collagen self-assembly. The procollagen molecule is represented by a straight line with bent (N-propeptide) and circular (C-propeptide) regions. Initial linear and lateral aggregation is promoted by the presence of both the N- and C-propeptides. In the presence of both propeptides lateral assembly is limited and the fibrils are narrow. Removal of the N-propeptide results in lateral assembly of narrow fibrils removal of the C-propeptide results in additional lateral growth of fibrils. As indicated in the diagram, the presence of the N- and C-propeptides physically interferes with fibril formation.

Silver FH, Freeman JW, Seehra GP. Collagen self-assembly and the development of tendon mechanical properties. I Biomech. 2003 36 1529. 

Veis A, George A. Fundamentals of Interstitial Collagen Self-Assembly. Extracellular Matrix Assembly. New York Academic Press 1994 15 15. 

Ward NP, Hulmes DJS, Chapman JA. Collagen self-assembly in vitro Electron microscopy of initial aggregates formed during the lag phase, I Mol Biol. 1986 190 107-112. 

A composite coating by electrolysis-induced collagen self-assembly and calcium phosphate mineralization. Biomaterials, 26,1623-32. 

The minerals form crystals through ionic bonding. Collagen self-assembly into fibrils is driven by all intermolecular forces, particularly hydrophilic-hydrophobic interactions. 

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