Apolipoproteins C-I, C-II, and C-III: Kinetics of Association with Model Membranes and Intermembrane Transfer

Barry J. Mckeone, John B. Massey, Roger D. Knapp, Henry J. Pownall

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

The apoproteins (apo) C-I, C-II, and C-III are low molecular weight amphiphilic proteins that are associated with the lipid surface of the plasma chylomicron, very low density lipoprotein (VLDL), and high-density lipoprotein (HDL) subfractions. Purified apoC-I spontaneously reassociates with VLDL, HDL, and single-bilayer vesicles (SBV) of l-palmitoyl-2-oleoyl-.sn-glycero-3-phosphocholine. ApoC-I also transfers reversibly from VLDL to HDL and from VLDL and HDL to SBV. The kinetics of association of the individual apoC proteins with SBV are second order overall and first order with respect to lipid and protein concentrations. At 37 °C, the rates of association were 2.5 × 1010, 4.0 × 1010 and 3.8 × 1010 M-1 s-1 for apoC-I, apoC-II, and apoC-III, respectively. Arrhenius plots of association rate vs temperature were linear and yielded activation energies of 11.0 (apoC-I), 9.0 (apoC-II), and 10.6 kcal/mol (apoC-III). The kinetics of vesicle to vesicle apoprotein transfer are biexponential for intermembrane transfer, indicating two concurrent transfer processes. Rate constants at 37 °C for the fast component of dissociation were 11.7, 9.5, and 9.9 s-1 while rate constants for the slow component were 1.3, 0.6, and 0.9 s-1 for apoC-I, apoC-II, and apoC-III, respectively. The dissociation constants, Kd, of apoC-I, apoC-II, and apoC-III bound to the surface monolayer of phospholipid-coated latex beads were 0.5, 1.4, and 0.5 μM, respectively. These studies show that the apoC proteins are in dynamic equilibrium among phospholipid surfaces on a time scale that is rapid compared to lipolysis, lipid transfer, and lipoprotein turnover.

Original languageEnglish (US)
Pages (from-to)4500-4505
Number of pages6
JournalBiochemistry
Volume27
Issue number12
DOIs
StatePublished - Jun 1 1988
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry

Fingerprint Dive into the research topics of 'Apolipoproteins C-I, C-II, and C-III: Kinetics of Association with Model Membranes and Intermembrane Transfer'. Together they form a unique fingerprint.

Cite this