Pepsin is known to cleave type 1 collagen. My question is, where within the collagen molecule does this occur. Is it only at one location or many?
Pepsin will cleave almost any kind of collagen in locations where the three alpha-chains are not interacting to form a stable triple-helical structure. Therefore pepsin is cleaving insoluble type I collagen only in the region of the telopeptides, provided the temperature and other conditions could ensure the stabilization of the remaining triple-helical arrangement.
Hi Michel, thanks for responding. I'm looking to measure (in absolute not relative values) the amount of collagen in the ECM of 3D cultured fibroblasts. I found an ELISA kit that requires solublization of type 1 collagen via pepsin treatment before it can be used. If you say that pepsin will only cleave the telopeptides, and the telopeptides are cleaved off after secretion anyway, does that mean this method can't be used to get this measurement?
Pepsin is cleaving at the remaining terminal nonhelical regions still present after procollagen peptidase activity and where the lysine-derived cross-links are located while ensuring further extracellular maturation/insolubilization of collagen. That's the way to get the full triplehelical portion of collagen in a soluble form available for its determination.