Apolipoprotein E: Phospholipid Binding Studies with Synthetic Peptides from the Carboxyl Terminus

James T. Sparrow, Doris A. Sparrow, Germain Fernando, Alan R. Culwell, Merry Kovar, Antonio Gotto

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

We have previously shown that the synthetic peptide apoE(129-169) forms lipid-peptide complexes with dimyristoylphosphatidylcholine (DMPC) with an L:P molar ratio of 125:1; the peptide in the isolated complex contains ∼56% α-helicity. These results verify the presence of an amphipathic α-helix in this region of apoE as predicted by Chou-Fasman analysis and hydrophobicity calculations. To further define the lipid binding regions of apoE, we have synthesized four peptides, apoE(211-243), -(202-243), -(267-286), and -(263-286), from the carboxyl terminus of apoE and studied their lipid binding properties; apoE(202-243) contains two potential amphipathic helices. Although all four peptides formed α-helices in the helix-forming solvent 30% hexafluoropropanol, we found that only apoE(263-286) formed a stable complex with DMPC. The peptide contained ∼80% α-helicity, and its Trp fluorescence spectrum was blue-shifted by 20 nm in the complex which had an L:P ratio of 163:1. We conclude that this sequence is a newly identified lipid binding region of apoE and that the amphipathic helices 203-221 and 226-243 are too hydrophilic to bind phospholipid.

Original languageEnglish (US)
Pages (from-to)1065-1068
Number of pages4
JournalBiochemistry
Volume31
Issue number4
DOIs
StatePublished - Feb 1 1992

ASJC Scopus subject areas

  • Biochemistry

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