Analysis of heparin-binding sites in human lipoprotein lipase using synthetic peptides

Synthetic nonbasic peptides based on the type I repeats of thrombospondin ( TSP) and four peptides corresponding to the predicted basic clusters in lip oprotein lipase (LPL) have been analyzed for heparin binding. In the presen t report we examine the structural requirement for the binding of these pep tides to heparin-Sepharose column. The peptide containing the sequence Phe- Ser-Trp-Ser-Asp-Trp-Trp-Ser (residues 388-395 in lipoprotein lipase, which include the consensus TSP type I sequence) showed strong binding to heparin . Both the first and second Trp residues in this sequence were essential fo r tight heparin binding. Substitution of either of the Trp residues by an A la resulted in the complete loss of heparin binding. The peptides represent ing the four basic cluster regions of lipoprotein lipase showed variable he parin binding. Strong retention was observed for peptides representing clus ter 1 (residues 261-287) and cluster 3 (residues 147-151) peptides followed by cluster 2 (residues 290-302) peptide. A peptide corresponding to LPL cl uster 4 (residues 405-414) did not show binding to heparin column. The pres ent study confirms the presence of specific heparin-binding sites in LPL. F urthermore, this study also demonstrates the potential use of synthetic pep tides to investigate the interaction between peptides and heparin as an alt ernative approach to site-directed mutagenesis in selected regions of large protein molecules. The affinity of these peptides toward heparin can be ex plored to block molecular interactions at these specific sites or to carry and deliver other coupled molecules at the site(s) of attachment of these p eptides for therapeutic applications.