ISSN:
0887-3585
Keywords:
lipid-protein complexes
;
molecular hydrophobicity potential
;
protein hydrophobicity
;
apolipoprotein
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
In this paper we propose a classification of the amphipathic helicalrepeats occurring in the plasma apolipoprotein sequences. It is based upon the calculation of the molecular hydrophobicity potential around the helical segments. The repeats were identified using a new autocorrelation matrix, based upon similarities of hydrophobic and hydrophilic properties of the amino acid residues within the apolipoprotein sequences. The helices were constructed by molecular modeling, the molecular hydrophobicity potential was calculated, and isopotential contour lines drawn around the helices yieldeda three-dimensional visualization of the hydrophobicity potential. Two classes of apolipoproteins could be differentiated by comparing the hydrophobic angles obtained by projection of the isopotential contour lines on a plane perpendicular to the long axis of the helix. The isopotential contour lines around apo AI, AIV, and E are more hydrophilic than hydrophobic, whereas they are of similar intensity for apo AII, CI, and CIII. In both cases discoidal lipid-protein complexes are generated, with the amphipathic helices around the edge of the lipid core. The long axis of the helices is oriented parallel to the phospholipid acyl chains and the hydrophilic side of the helix toward the aqueous phase. As a result of the differences in hydrophobicity potential, the contact between the hydrophobic side of the helices and the phospholipid acyl chains is larger for apo AII, CI, and CIII than for the other apolipoproteins. This might account for the greater stability of the discoidal complexes generated between phospholipids and these apoproteins. © 1992 Wiley-Liss, Inc.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prot.340130307
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