Thermodynamics of lipid protein associations. Thermodynamics of helix formation in the association of high density apolipoprotein A-I (apoA-I) to dimyristoyl phosphatidylcholine. Academic Article uri icon

Overview

abstract

  • The structure and phospholipid-binding properties of human plasma high density apolipoprotein A-I (apoA-I) has been studied at pH 7.4 and 3.1 by microcalorimetry, circular dichroism and density gradient ultracentrifugation. At pH values of 7.4 and 3.1, apoA-I binds to dimyristoyl phosphatidylcholine (DMPC) to form complexes of similar composition (molar ratio of DMPC/apoA-I of 100) and helical content (67%). At pH 7.4, the lipid-protein association is accompanied by an increase in helical content from 58 to 67% and an exothermic enthalpy of binding (deltaHB) of -90 kcal/mol apoA-I. At pH 3.1, the helical content of apoA-I is increased from 48 to 67% on binding to DMPC and the enthalpy of binding was -170 kcal/mol. We suggest that the difference in the enthalpies of binding (-80 kcal/mol) at pH 3.1 compared to 7.4 is due to the greater coil leads to helix transition at the lower pH.

publication date

  • August 24, 1977

Research

keywords

  • Apolipoproteins
  • Lipoproteins, HDL
  • Phosphatidylcholines

Identity

Scopus Document Identifier

  • 0017645817

Digital Object Identifier (DOI)

  • 10.1016/0005-2760(77)90176-x

PubMed ID

  • 19081

Additional Document Info

volume

  • 488

issue

  • 2