Contribution of the Carboxy-Terminal Domain of Lipoprotein Lipase to Interaction with Heparin and Lipoproteins
Abstract
The C-terminal domain of lipoprotein lipase (LPL) is involved in several important interactions. To assess its contribution to the binding ability of full-length LPL we have determined kinetic constants using biosensor technique. The affinity of the C-terminal domain for heparin was about 500-fold lower than that of full-length LPL (Kd = 1.3 μM compared to 3.1 nM). Replacement of Lys403, Arg405 and Lys407 by Ala abolished the heparin affinity, whereas replacement of Arg420 and Lys422 had little effect. The C-terminal domain increased binding of chylomicrons and VLDL to immobilized heparin relatively well, but was less than 10% efficient in binding of LDL compared to full-length LPL. Deletion of residues 390–393 (WSDW) did not change the affinity to heparin and only slightly decreased the affinity to lipoproteins. We conclude that the C-terminal folding domain contributes only moderately to the heparin affinity of full-length LPL, whereas the domain appears important for tethering triglyceride-rich lipoproteins to heparin-bound LPL.
- Publication:
-
Biochemical and Biophysical Research Communications
- Pub Date:
- April 2000
- DOI:
- Bibcode:
- 2000BBRC..271...15L
- Keywords:
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- surface plasmon resonance technique;
- affinity constants;
- heparan sulfate;
- ionic interaction;
- mutants