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Study on the composition-structure relationship of lipophorins
1Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CONICET-UNLP, Facultad de Ciencias Médicas, La Plata, Argentina.
Journal of Lipid Research
|March 1, 1991
Summary
High density lipophorin (HDLp) in insect hemolymph has a defined structure with a protein-rich outer layer and lipid-rich core. This structure is maintained despite variations in lipid composition, revealing unifying organizational principles.
Area of Science:
- Biochemistry
- Structural Biology
- Insect Physiology
Background:
- High density lipophorin (HDLp) is the primary lipoprotein in insect hemolymph.
- HDLp comprises two apolipoproteins (apoLp-I and apoLp-II) and variable lipid content (35-59%).
- Key lipids include diacylglycerols (DG), phospholipids (PL), and hydrocarbons (HC), with minor cholesterol and triacylglycerols (TG).
Purpose of the Study:
- To elucidate the relationship between lipid composition and the structural arrangement of HDLp.
- To develop and validate a density-composition structural model for HDLp.
- To identify unifying structural principles governing HDLp organization.
Main Methods:
- Development of a density-composition structural model for HDLp.
- Utilized 12 datasets on lipophorin density-composition relationships.
- Validated the model based on lipoprotein space- and surface-filling conditions.
Main Results:
- HDLp particles are spherical with a protein-rich outer layer (approx. 20-21 Å thick) and a lipid-rich core.
- The outer layer contains proteins, PL, cholesterol, and some DG.
- The core consists of HC, TG, and the majority of DG.
Conclusions:
- Despite compositional variations, HDLp exhibits consistent structural restrictions.
- Apolipophorins are localized within the lipid-rich core, potentially possessing beta-shift structure and strong hydrophobic interactions.
- The model provides quantitative insights into the molecular organization of insect lipophorins.