Some physicochemical properties of calfskin pepsin-solubilized collagen (PSC) and succinylated PSC (SPSC) were compared. The amino acid profile remained significantly unchanged. Sodium dodecylsulphate-polyacrylamide gel electrophoresis showed that subunits of SPSC migrated less than those of PSC. The denaturation temperatures of PSC and SPSC were 38.4 degrees C and 34.7 degrees C respectively. Succinylation slightly altered the triple-helical conformation of collagen, as determined by circular dichroism.