title: Interaction of synthetic N-5-dimethylaminonaphthalene-1-sulfonyl-apolipoprotein C-II peptides with lipoprotein lipase.
abstract: Synthetic fragments of apo-C-II, specifically labeled on their NH2-terminals with the 5-dimethylaminonaphthalene-1-sulfonyl (dansyl or DNS) fluorophore, have been prepared by solid phase peptide synthesis. When a complex is formed between bovine milk lipoprotein lipase and N-dansyl-apo-C-II peptides, resonance energy transfer occurs from the tryptophan residues of the enzyme to the dansyl-labeled peptides upon excitation at 280 nm. In the absence of lipid, the association constant increases 10-fold when the length of the DNS peptide is increased from apo-C-II-DNS(64-78) (0.04 X 10(6) M-1) to apo-C-II-DNS(60-78) (0.3 X 10(6) M-1). In the presence of lipid, the association constants are dependent on peptide chain length, and increase from 0.4 X 10(6) M-1 for apo-C-II-DNS(64-78) to 2.2 X 10(7) M-1 for apo-C-II-DNS(43-78). The interactions are specific for lipoprotein lipase, are disrupted by guanidinium chloride, are not affected by 1.0 M NaCl, and are competitive with the corresponding nondansylated peptide. Apolipoproteins C-III and A-I, at 5 to 1 molar ratios, had no effect on the interaction. These findings demonstrate the importance of the COOH-terminal region in the lipoprotein lipase-apo-C-II interaction and show that activation of the enzyme involves a specific protein-protein interaction.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D053304:Apolipoprotein C-II; D001053:Apolipoproteins / Q000378:metabolism*; D001056:Apolipoproteins C; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D003619:Dansyl Compounds / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007700:Kinetics; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008433:Mathematics; D008892:Milk / Q000201:enzymology; D010446:Peptide Fragments / Q000378:metabolism
chemical_list: D000596:Amino Acids; D053304:Apolipoprotein C-II; D001053:Apolipoproteins; D001056:Apolipoproteins C; D003619:Dansyl Compounds; D010446:Peptide Fragments; D008071:Lipoprotein Lipase