An alternate apoprotein conformation in high density apolipoprotein discoidal complexes. A Fourier transform infra-red study.
Discoidal complexes have been prepared from 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and the apoproteins of HDL3 (apo HDL3) or purified apo A-I. Gel electrophoresis established that apo HDL3 contained 74% apo A-I. Deconvolution and curve-fitting of the infra-red amide I band of the apoprotein in the lipid-protein complex revealed a secondary structure containing approximately 40% alpha-helix and 50% beta-structure. This contrasted with the results from circular dichroism studies (Surewicz et al. (1986) J. Biol. Chem., 261, 16191) of apo A-I/DMPC complexes which predicted 68% alpha-helix and 7% beta-structure. The discrepancy between the two methods and limitations of the two techniques for lipoproteins is discussed.
Yang
J Y
JY
Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada.
Treleaven
W D
WD
Cushley
R J
RJ
D016632:Apolipoprotein A-I / Q000737:chemistry*; D001053:Apolipoproteins / Q000737:chemistry*; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D005583:Fourier Analysis; D008075:Lipoproteins, HDL / Q000737:chemistry*; D053440:Lipoproteins, HDL3; D008970:Molecular Weight; D011487:Protein Conformation
D016632:Apolipoprotein A-I; D001053:Apolipoproteins; D008075:Lipoproteins, HDL; D053440:Lipoproteins, HDL3; D004134:Dimyristoylphosphatidylcholine