Molecular structure of an apolipoprotein determined at 2. 5- angstrom resolution

Journal Article · Tue Jan 22 00:00:00 EST 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00217a002· OSTI ID:5397454

Breiter, D R; Benning, M M; Wesenberg, G; Holden, H M; Rayment, I ^[1]; Kanost, M R; Law, J H; Wells, M A ^[2]

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1. Univ. of Wisconsin, Madison (USA)
2. Univ. of Arizona, Tucson (USA)

The three-dimensional structure of an apolipoprotein isolated from the African migratory locust Locusta migratoria has been determined by X-ray analysis to a resolution of 2.5 {angstrom}. The overall molecular architecture of this protein consists of five long {alpha}-helices connected by short loops. As predicted from amino acid sequence analyses, these helices are distinctly amphiphilic with the hydrophobic residues pointing in toward the interior of the protein and the hydrophilic side chains facing outward. The molecule falls into the general category of up-and-down {alpha}-helical bundles as previously observed, for example, in cytochrome c{prime}. Although the structure shows the presence of five long amphiphilic {alpha}-helices, the {alpha}-helical moment and hydrophobicity of the entire molecule fall into the range found for normal globular proteins. Thus, in order for the amphiphilic helices to play a role in the binding of the protein to a lipid surface, there must be a structural reorganization of the protein which exposes the hydrophobic interior to the lipid surface. The three dimensional motif of this apolipoprotein is compatible with a model in which the molecule binds to the lipid surface via a relatively nonpolar end and then spreads on the surface in such a way as to cause the hydrophobic side chains of the helices to come in contact with the lipid surface, the charged and polar residues to remain in contact with water, and the overall helical motif of the protein to be maintained.

• OSTI ID: 5397454
• Journal Information: Biochemistry; (United States), Vol. 30:3; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
APOLIPOPROTEINS
X-RAY DIFFRACTION
ELECTRON DENSITY
LOCUSTS
MOLECULAR MODELS
MOLECULAR STRUCTURE
STEREOCHEMISTRY
ANIMALS
ARTHROPODS
COHERENT SCATTERING
DIFFRACTION
GRASSHOPPERS
INSECTS
INVERTEBRATES
LIPIDS
LIPOPROTEINS
MATHEMATICAL MODELS
ORGANIC COMPOUNDS
ORTHOPTERA
PROTEINS
SCATTERING
550602* - Medicine- External Radiation in Diagnostics- (1980-)