PMID: 3759983Oct 15, 1986Paper

Physical and surface properties of insect apolipophorin III.

The Journal of Biological Chemistry
J K KawooyaJ H Law

Abstract

Apolipophorin III (apoLp-III) from Manduca sexta has a molecular weight of 18,100. Based on its hydrodynamic properties (sedimentation and diffusion coefficients, frictional ratio, intrinsic viscosity) and its behavior during gel permeation chromatography, we concluded that apoLp-III is a prolate ellipsoid with an axial ratio of about 3. The circular dichroic spectrum of apoLp-III suggests that the protein contains approximately 50% alpha-helix. At the air-water interface, apoLp-III forms a monolayer which is gaseous at surface pressures less than or equal to 1 dyne/cm. The isotherm of this phase yields an excluded molecular area of 3800 A2/molecule (23 A2/amino acid). At a surface pressure of 22.1 dynes/cm, the monolayer undergoes a phase transition reminiscent of a first-order phase transition of pure lipids. The monolayer can be compressed in this surface pressure range to an area per molecule of 480 A2 (2.9 A2/amino acid). Since a globular protein of molecular weight 18,100 could occupy an area of only about 2000 A2 when bound to a surface, it is suggested that in the expanded state, apoLp-III must unfold on the surface, whereas in the compressed state, the molecule is oriented with its minor axis parallel to the water surf...Continue Reading

Related Concepts

Related Feeds

ASBMB Publications

The American Society for Biochemistry and Molecular Biology (ASBMB) includes the Journal of Biological Chemistry, Molecular & Cellular Proteomics, and the Journal of Lipid Research. Discover the latest research from ASBMB here.

ApoE, Lipids & Cholesterol

Serum cholesterol, triglycerides, apolipoprotein B (APOB)-containing lipoproteins (very low-density lipoprotein (VLDL), immediate-density lipoprotein (IDL), and low-density lipoprotein (LDL), lipoprotein A (LPA)) and the total cholesterol/high-density lipoprotein (HDL) cholesterol ratio are all connected in diseases. Here is the latest research.