Hydration and density of collagen and gelatin

摘要

AbstractThe water sorption by adult and embryonic native and insoluble collagen was investigated, along with that of calfskin gelatin. Greater sorption was obtainable with the collagen fractions than with gelatin, but the technique could not distinguish the fractions themselves. The suggestion is made that the greater sorption by collagen over gelatin and differences in apparent wettability between the adult and embryonic insoluble collagen might be explained by the formation of helical grooves with aging. Density measurements of the collagen fractions indicate that collagen becomes more crystalline with aging. This also applied to the insoluble collagen. These results are consistent with the view that differences in collagen solubility are due to differences in molecular ordering. The density of the insoluble collagens and gelatin passes through a maximum at 3–4 sorbed water. The phenomenon is explained on the basis of water bridges comprised of a single water molecule double hydrogen bonded to closely aligned chains. A discussion is presented in this connection. A calculation based on the density yields a molecular volume of 4.32 × 10−19cm.3For tropocollagen. This is in agreement with the molecular dimensions and consistent with the idea that collagen is formed from an aggregation of the mon