(A) PlnDI binding to collagen I fibrils. Binding of biotinylated PlnDI was determined as described in Materials and Methods. The bar graph indicates means ± SD of triplicate determinations of PlnDI, PlnDI digested with heparinases I, II, and III (HEPN), and PlnDI digested with chondroitinase AC (CHON) to collagen I fibrils. Collagen I fibrils incubated in PBS without binding interaction with PlnDI served as control. *p ± 0.01 relative to undigested or chondroitinase-digested PlnDI. (B) FGF-2 binding to PlnDI associated with collagen I fibrils. PlnDI and PlnDI digested with heparinases I, II, and III (HEPN) interact with collagen I fibrils to form PF (PlnDI-fibrils) and D-PF (digested PlnDI-fibrils), respectively. These complexes were used as matrices for FGF-2 binding. FGF-2 binding was determined by ELISA as described in Materials and Methods. Each bar indicates the mean ± SD of triplicate determinations.