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A structural core within apolipoprotein C-II amyloid fibrils identified using hydrogen exchange and proteolysis.
- Source :
-
Journal of molecular biology [J Mol Biol] 2007 Mar 09; Vol. 366 (5), pp. 1639-51. Date of Electronic Publication: 2006 Dec 21. - Publication Year :
- 2007
-
Abstract
- Plasma apolipoproteins show alpha-helical structure in the lipid-bound state and limited conformational stability in the absence of lipid. This structural instability of lipid-free apolipoproteins may account for the high propensity of apolipoproteins to aggregate and accumulate in disease-related amyloid deposits. Here, we explore the properties of amyloid fibrils formed by apolipoproteins using human apolipoprotein (apo) C-II as a model system. Hydrogen-deuterium exchange and NMR spectroscopy of apoC-II fibrils revealed core regions between residues 19-37 and 57-74 with reduced amide proton exchange rates compared to monomeric apoC-II. The C-terminal core region was also identified by partial proteolysis of apoC-II amyloid fibrils using endoproteinase GluC and proteinase K. Complete tryptic hydrolysis of apoC-II fibrils followed by centrifugation yielded a single peptide in the pellet fraction identified using mass spectrometry as apoC-II(56-76). Synthetic apoC-II(56-76) readily formed fibrils, albeit with a different morphology and thioflavinT fluorescence yield compared to full-length apoC-II. Studies with smaller peptides narrowed this fibril-forming core to a region within residues 60-70. We postulate that the ability of apoC-II(60-70) to independently form amyloid fibrils drives fibril formation by apoC-II. These specific amyloid-forming regions within apolipoproteins may underlie the propensity of apolipoproteins and their peptide derivatives to accumulate in amyloid deposits in vivo.
- Subjects :
- Amino Acid Motifs
Amino Acid Sequence
Amyloid ultrastructure
Apolipoprotein C-II isolation & purification
Apolipoprotein C-II ultrastructure
Benzothiazoles
Chromatography, High Pressure Liquid
Circular Dichroism
Deuterium Exchange Measurement
Dose-Response Relationship, Drug
Electrophoresis, Agar Gel
Endopeptidase K pharmacology
Fluorescent Dyes
Humans
Hydrolysis
Kinetics
Mass Spectrometry
Molecular Sequence Data
Nuclear Magnetic Resonance, Biomolecular
Protein Conformation
Protein Folding
Protein Structure, Tertiary
Serine Endopeptidases pharmacology
Spectrometry, Fluorescence
Thiazoles
Time Factors
Trypsin pharmacology
Amyloid chemistry
Apolipoprotein C-II chemistry
Deuterium metabolism
Hydrogen metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0022-2836
- Volume :
- 366
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- Journal of molecular biology
- Publication Type :
- Academic Journal
- Accession number :
- 17217959
- Full Text :
- https://doi.org/10.1016/j.jmb.2006.12.040