Different behavior of type I and type I-trimer collagen in neutral sodium chloride solutions.

Type I and type I-trimer collagen, isolated from ductal infiltrating carcinoma of the human breast, have been tested for their behavior in neutral NaCl solutions. Evident diversities in their rate of precipitation at different saline concentrations have been found, since type I-trimer collagen precipitates at low NaCl molarity while type I collagen is mostly recovered in 2.6-3.6 M NaCl solutions. The native conformation of homotrimer collagen is proved by its ability to produce segment long-spacing crystallites and native-type fibrils.