Reduced dimerization of lipoprotein lipase in post-heparin plasma of a patient with hyperchylomicronemia.
As in post-heparin plasma of control subjects, post-heparin plasma of a patient with hyperchylomicronemia contained lipoprotein lipase (LPL) subunits with M(r) = 57,000. But although the amount of LPL was the same as in post-heparin plasma of controls, no LPL activity was detectable. Nearly all the LPL in post-heparin plasma of controls bound to heparin-Sepharose and this LPL bound was mainly eluted with 1.5 M NaCl in parallel with the activity. In post-heparin plasma of the patient, 58% of the LPL subunits did not bind to heparin-Sepharose and 23% was eluted with 0.6 M NaCl. Studies by sucrose density gradient centrifugation showed that almost all the LPL in post-heparin plasma of controls was recovered in the peak with a sedimentation coefficient of 6.8 S, corresponding to the position of a dimeric form of LPL, in parallel with the activity; little LPL was recovered in the peak with a sedimentation coefficient of 4.0 S, corresponding to the position of a monomeric form of LPL. In post-heparin plasma of the patient, 35% of the LPL subunits was recovered in fractions with larger sedimentation coefficients at the bottom of the centrifuge tube, indicating the presence of an aggregated form(s) of LPL; the amount of the monomeric form of LPL was increased, while that of the dimeric form was decreased. Thus, defect of LPL activity in post-heparin plasma of the patient with hyperchylomicronemia could result from reduced dimerization of LPL subunits.
Masuno
H
H
Department of Medical Laboratory Technology, Ehime College of Health Science, Japan.
Nakabayashi
H
H
Kobayashi
J
J
Saito
Y
Y
Okuda
H
H
D000293:Adolescent; D015153:Blotting, Western; D002845:Chromatography; D005260:Female; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D008072:Hyperlipoproteinemia Type I / Q000201:enzymology*; D008071:Lipoprotein Lipase / Q000097:blood / Q000737:chemistry*; D015394:Molecular Structure
D006493:Heparin; D008071:Lipoprotein Lipase