Activation of lipoprotein lipase by native and synthetic fragments of human plasma apolipoprotein C-II.
Apolipoprotein C-II (apoC-II), a protein constituent of human very low density lipoproteins, is the activator for lipoprotein lipase (LPL; triacylglycerol acyl-hydrolase, EC 3.1.1.3). The amino acid sequence of the 78 residues of apoC-II has recently been established in this laboratory. To determine the minimal sequence requirements for activation, we have prepared both native and synthetic fragments of apoC-II and tested them for their ability to activate LPL. Cyanogen bromide fragments of apoC-II corresponding to residues 1--9 and 10--59 had little ability to activate LPL. However, the COOH-terminal cyanogen bromide fragment corresponding to residues 60--78 increased hydrolysis 4-fold compared to an average of 9-fold activation for the same concentration of apoC-II. The synthetic peptide containing residues 60--78 prepared by solid-phase techniques enhanced the lipolysis 3-fold. Addition of five residues produced a synthetic fragment 55--78 that enhanced the release of fatty acid 12-fold compared to 13-fold for intact apoC-II. By contrast, the synthetic peptide containing residues 66--78 did not activate. Removal of the three COOH-terminal residues, Gly-Glu-Glu, from fragment 60--78 decreased the ability to activate LPL by greater than 95%. These studies suggest that the maximal activation of LPL by apoC-II requires a minimal sequence contained within residues 55--78.
D000595:Amino Acid Sequence; D001053:Apolipoproteins / Q000494:pharmacology*; D055598:Chemical Phenomena; D002621:Chemistry; D003488:Cyanogen Bromide; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D006858:Hydrofluoric Acid; D006868:Hydrolysis; D008071:Lipoprotein Lipase / Q000378:metabolism*; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000302:isolation & purification / Q000494:pharmacology; D013329:Structure-Activity Relationship
D001053:Apolipoproteins; D010446:Peptide Fragments; D008071:Lipoprotein Lipase; D003488:Cyanogen Bromide; D006858:Hydrofluoric Acid
Proc Natl Acad Sci U S A. 1977 May;74(5):1942-5
194244
Med Biol. 1977 Jun;55(3):187-91
895217
Biochemistry. 1973 Apr 24;12(9):1828-33
4349259
Proc Natl Acad Sci U S A. 1976 May;73(5):1422-6
179085
Physiol Rev. 1976 Apr;56(2):259-316
180553
Clin Chim Acta. 1975 Sep 16;63(3):335-47
240522
J Lipid Res. 1976 May;17(3):248-56
180220
J Biol Chem. 1973 May 10;248(9):3359-62
4735583
Biochim Biophys Acta. 1970 Mar 31;200(3):573-5
4985344
J Org Chem. 1976 Apr 16;41(8):1350-3
1263004
Biochem J. 1975 Sep;149(3):649-55
1239278
Biochem Biophys Res Commun. 1970 Oct 9;41(1):57-62
5459123
Biochemistry. 1969 Nov;8(11):4510-6
5353112