Glycosaminoglycan and collagen facilitate the degradation of pigment epithelium-derived factor by chymotrypsin.

Pigment epithelium-derived factor (PEDF) is a member of the serine protease inhibitor family. It is present in a variety of tissues and organs, including plasma. Here, PEDF was purified from human plasma by use of a dermatan sulfate affinity column, and then hydroxyapatite, gel filtration and ion exchange columns. It did not form a complex with various proteases, including chymotrypsin, elastase, kallikrein, thrombin, plasmin, cathepsins G, activated protein C, and urokinase, but collagen type I facilitated the degradation of PEDF by chymotrypsin more than 10-fold. Dermatan sulfate, heparan sulfate, and heparin showed similar effects, but other glycosaminoglycans, such as hyaluronic acid, chondroitin sulfate A, C, D, E, and keratan sulfate, had no effect on PEDF degradation.