Thermodynamics of dihexanoylphosphatidylcholine aggregation

Johnson, Robert E.; Wells, Michael A.; Rupley, John A.

doi:10.1021/bi00517a044

Cited by 29 publications

(17 citation statements)

References 16 publications

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“…The sigmoidal titration curve de¢nes a cooperative transition with a midpoint at approximately 6 mM DHPC. This concentration is signi¢cantly lower than the values of 10^16 mM reported for the critical micelle concentration (CMC) of DHPC [14]. Sedimentation equilibrium experiments with varying concentrations of DHPC under the conditions used in Fig.…”

Section: Spectroscopic Analysis Of the Interaction Of Apoc-ii Withmentioning

confidence: 70%

Sub‐micellar phospholipid accelerates amyloid formation by apolipoprotein C‐II

2001

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Lipid-free human apolipoprotein C-II (apoC-II) forms amyloid fibrils with characteristic L L-structure. This conformation is distinct from the K K-helical fold of lipid-bound apoC-II. We have investigated the effect of the short-chain phospholipid, dihexanoylphosphatidylcholine (DHPC) on amyloid formation by apoC-II. The K K-helical content of apoC-II increases in the presence of micellar DHPC (16 mM) and amyloid formation is inhibited. However, at sub-micellar DHPC concentrations (below 8 mM) amyloid formation is accelerated 6 fold. These results suggest that individual phospholipid molecules in vivo may exert significant effects on amyloid folding pathways. ß 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

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Section: Spectroscopic Analysis Of the Interaction Of Apoc-ii Withmentioning

confidence: 70%

Sub‐micellar phospholipid accelerates amyloid formation by apolipoprotein C‐II

2001

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“…3 shows an expanded form of the ~3C-NMR spectrum of anomeric (C-l) carbon atoms of the HFextracted polysaccharide. Anomeric carbons with glycosidic linkages in the alpha configurations usually have signals (resonances) in the range between 99 and 102 ppm, while those with /3 configurations have signals between 102 and 105 ppm [16][17][18]. Also coupling constants (IJc-H) of 261 about 170 Hz are displayed by a pyranosides, whereas fi pyranosides display coupling constants of about 160 Hz [19,20].…”

Section: Resultsmentioning

confidence: 99%

Isolation and purification of cell wall polysaccharide of Bacillus anthracis (Δ Sterne)

Ekwunife¹

1991

FEMS Microbiology Letters

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A polysaccharide fraction was isolated form sodium-dodecyl-sulfate (SDS) treated cell walls of Bacillus anthracis (delta Sterne) by hydrofluoric acid (HF) hydrolysis and ethanolic precipitation. The polysaccharide fraction was subsequently purified by several washings with absolute ethanol. Purity of the isolated polysaccharide was tested using the anthrone assay and amino acid analyzer. The molecular mass of the polysaccharide fraction as determined by gel filtration chromatography was about 12000 Da. Preliminary analyses of the polysaccharide was done using thin layer chromatography and amino acid analyzer, and results obtained from these analyses were further confirmed by gas liquid chromatography and 13C-NMR spectroscopy. Results showed that the polysaccharide moiety contained galactose, N-acetylglucosamine, and N-acetylmannosamine in an approximate molar ratio of 3:2:1. This moiety was devoid of muramic acid, alanine, diaminopimelic acid, glutamic acid, and lipid, thus indicating that the isolated polysaccharide was of pure quality.

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“…NMR spectroscopy, sedimentation equilibrium, and microcalorimetry data indicate that DHPC micelle formation proceeds via the formation of a dimeric intermediate (30,32). Sedimentation equilibrium experiments were carried out to provide a more complete analysis of the micellar state of DHPS (Fig.…”

Section: The Effect Of Dhpc and Dhps On Apoc-ii Fibril Formation-mentioning

confidence: 99%

Fluorescence Detection of a Lipid-induced Tetrameric Intermediate in Amyloid Fibril Formation by Apolipoprotein C-II

Ryan

Howlett

Bailey

2008

Journal of Biological Chemistry

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The misfolding and self-assembly of proteins into amyloid fibrils that occurs in several debilitating and age-related diseases is affected by common components of amyloid deposits, notably lipids and lipid complexes. We have examined the effect of the short-chain phospholipids, dihexanoylphosphatidylcholine (DHPC) and dihexanoylphosphatidylserine (DHPS), on amyloid fibril formation by human apolipoprotein C-II (apoC-II). Micellar DHPC and DHPS strongly inhibited apoC-II fibril formation, whereas submicellar levels of these lipids accelerated apoC-II fibril formation to a similar degree. These results indicate that the net negative charge on DHPS, compared with the neutrally charged DHPC, is not critical for either the inhibition or activation process. We also investigated the mechanism for the submicellar, lipid-induced activation of fibril formation. Emission data for fluorescently labeled apoC-II indicated that DHPC and DHPS stimulate the early formation and accumulation of oligomeric species. Sedimentation velocity and equilibrium experiments using a new fluorescence detection system identified a discrete lipid-induced tetramer formed at low apoC-II concentrations in the absence of significant fibril formation. Seeding experiments showed that this tetramer was on the fibril-forming pathway. Fluorescence resonance energy transfer experiments established that this tetramer forms rapidly and is stabilized by submicellar, but not micellar, concentrations of DHPC and DHPS. Several recent studies show that oligomeric intermediates in amyloid fibril formation are toxic. Our results indicate that lipids promote on-pathway intermediates of apoC-II fibril assembly and that the accumulation of a discrete tetrameric intermediate depends on the molecular state of the lipid.Amyloid fibrils are formed by the self-assembly of naturally occurring proteins that misfold and aggregate into structures that share a number of common properties. The defining characteristics include increased ␤-structure compared with the native form of the protein, a fibrillar cross-␤-morphology, and the ability to interact with the dyes thioflavin T and Congo Red (1). The presence of specific fibrils in amyloid deposits associated with common neurodegenerative diseases, including Alzheimer and Parkinson diseases, has drawn considerable attention to the factors that affect amyloid fibril formation and the role of these fibrils in disease. Several factors within amyloid plaques exert effects on fibril formation, including metal ions, glycosaminoglycans, and proteins, such as serum amyloid P and apolipoprotein E (2). One important factor is the presence of lipids and lipid complexes, which are common components of all amyloid deposits. Fibrillogenesis by the A␤ 2 peptide (3), ␣-synuclein (4), or the islet amyloid polypeptide (5) is increased significantly by phospholipids in a manner that depends on the net charge of the phospholipid. Lipid bilayers composed of negatively charged phosphatidylserine or other anionic phospholipids accelerate amyloid fib...

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Thermodynamics of dihexanoylphosphatidylcholine aggregation

Cited by 29 publications

References 16 publications

Sub‐micellar phospholipid accelerates amyloid formation by apolipoprotein C‐II

Sub‐micellar phospholipid accelerates amyloid formation by apolipoprotein C‐II

Isolation and purification of cell wall polysaccharide of Bacillus anthracis (Δ Sterne)

Fluorescence Detection of a Lipid-induced Tetrameric Intermediate in Amyloid Fibril Formation by Apolipoprotein C-II

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