The acid relaxed collagen fiber was prepared from pigskin, which was unhaired, pretreated with A.S.1398 protease and sodium borohydride. The pretreated pigskin was relaxed in the dilute acetic acid system, and the relaxed mass was dispersed, neutralized and ice dried to prepare acid relaxed collagen fiber. The purity and properties of the fiber were determined. The results showed that the yield could reach 47.8% on the basis of dry weight. According to the electrophoresis and amino acid analysis results, except a little amount cystine existed, the fibers have good purity. The thermal denaturation temperature of the fiber was 58.2 ℃, and its isoelectric point was 7.44, which determined by Zeta potential determination method, and its natural triple helix conformation was maintained according to the circular dichroism and FT-IR results.
