Salts and amino acids as stabilising agents for reconstituted collagen fibres

Collagen fibres have been reconstituted by warming neutralised collagen solutions in the presence of various relevant substances, and their ease of dispersion in KI and urea subsequently determined. Of the substances which appeared to inhibit resolubilisation of the fibres, a particular study was made of salts and amino acids. Anion and cation series were obtained showing the relative effect of ions, which is probably a consequence of their salting-out potency. All the amino acids tested had a similar, weakly inhibiting effect on fibre redispersion. Kinetic studies showed that the amino acids stabilise the soluble collagen against precipitation but that the fibres once formed are less easily dispersed than controls. The inhibition of dispersion by serine is maximal at pH 6.5 and it is postulated that under these condition the charge properties of the two ampholytes are summated in such a way that non-specific cross-linkage during fibre formation is suppressed, allowing the formation of specific cross-links. It cannot be assumed that similar effects operate in vivo, but it is obvious that every simple connective-tissue components may quite markedly influence the properties of collagen fibres.