SAXS-WAXS monitoring of the amyloid fibril assembly of a hormone peptide analogue upon pH change.

A1thought the mechanisms of amyloidogenesis have not been entirely clarified, proteolysis of the parent proteins may be one of the important steps in the amyloid fibril formation. Recently, we reported that "dense fibrillar inclusions" (DFI), which had the characteristics of lysosomes and contained organized fibrillar profiles as well, were observed in the reticuloendothelial cells in close association with the foci of new amyloid deposits. We considered the findings as evidence for the involvement of lysosomal system in amyloid fibril formation (l). In the present study, we attempted to determine the identity of the contents of the DFI by the use of antisera against the amyloid protein (AA) and an immuno-electron microscopic technique.Amyloidosis was induced in CBA/J mice by daily injections of casein (l). AA was isolated from amyloid-laden spleens by gel filtration and antibody to it was produced in rabbits (2). For immunocytochemistry, the unlabeled antibody enzyme method (3) was employed.

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Effect of pH and inhibitors on beta-amyloid fibril assembly

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100166221 ◽

1996 ◽

Vol 54 ◽

pp. 752-753

Author(s):

Beverly E. Maleeff ◽

Timothy K. Hart ◽

Stephen J. Wood ◽

Ronald Wetzel

Keyword(s):

Amyloid Fibril ◽

Peptide Fragment ◽

Hydrophobic Peptides ◽

Amyloid Fibril Formation ◽

Effects Of Ph ◽

Severity Of The Disease ◽

Kinetics Of ◽

The Brain

Alzheimer's disease is characterized post-mortem in part by abnormal extracellular neuritic plaques found in brain tissue. There appears to be a correlation between the severity of Alzheimer's dementia in vivo and the number of plaques found in particular areas of the brain. These plaques are known to be the deposition sites of fibrils of the protein β-amyloid. It is thought that if the assembly of these plaques could be inhibited, the severity of the disease would be decreased. The peptide fragment Aβ, a precursor of the p-amyloid protein, has a 40 amino acid sequence, and has been shown to be toxic to neuronal cells in culture after an aging process of several days. This toxicity corresponds to the kinetics of in vitro amyloid fibril formation. In this study, we report the biochemical and ultrastructural effects of pH and the inhibitory agent hexadecyl-N-methylpiperidinium (HMP) bromide, one of a class of ionic micellar detergents known to be capable of solubilizing hydrophobic peptides, on the in vitro assembly of the peptide fragment Aβ.

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Faculty Opinions recommendation of Molecular conformation of a peptide fragment of transthyretin in an amyloid fibril.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1010558.176464 ◽

2002 ◽

Author(s):

H Jane Dyson

Keyword(s):

Amyloid Fibril ◽

Molecular Conformation ◽

Peptide Fragment

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Faculty Opinions recommendation of Amyloid fibril formation of alpha-synuclein is accelerated by preformed amyloid seeds of other proteins: implications for the mechanism of transmissible conformational diseases.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1028776.342335 ◽

2005 ◽

Author(s):

George Perry

Keyword(s):

Amyloid Fibril ◽

Alpha Synuclein ◽

Fibril Formation ◽

Conformational Diseases ◽

Amyloid Fibril Formation

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Faculty Opinions recommendation of Structure-based design of non-natural amino-acid inhibitors of amyloid fibril formation.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.11466956.14747140 ◽

2011 ◽

Author(s):

Francis Tsai ◽

Amadeo Biter

Keyword(s):

Amino Acid ◽

Amyloid Fibril ◽

Fibril Formation ◽

Natural Amino Acid ◽

Amyloid Fibril Formation

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Faculty Opinions recommendation of Experimental characterization of disordered and ordered aggregates populated during the process of amyloid fibril formation.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1159529.619907 ◽

2009 ◽

Author(s):

Stephen Eyles

Keyword(s):

Amyloid Fibril ◽

Fibril Formation ◽

Experimental Characterization ◽

Amyloid Fibril Formation

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Effect of pH and NH4NO3 as a Spray Additive on Penetration of NAA Through Isolated Tomato Fruit Cuticle

HortScience ◽

10.21273/hortsci.33.3.550a ◽

1998 ◽

Vol 33 (3) ◽

pp. 550a-550 ◽

Cited By ~ 1

Author(s):

Royal G. Fader ◽

Martin J. Bukovac

Keyword(s):

Direct Measurement ◽

Sodium Citrate ◽

Tomato Fruit ◽

Initial Slope ◽

Control Effect ◽

Solution Ph ◽

Ph Change ◽

Effect Of Ph ◽

Spray Droplets ◽

Partition Behavior

We have reported that NH4NO3 (AN, 8 mM, pH 4.2), applied as simulated spray droplets, enhanced penetration of 14C-NAA through isolated leaf and fruit cuticles. One explanation for this response is that AN depresses NAA (pKa= 4.2) dissociation, increasing the nondissociated moiety, which penetrates more readily than the anion (NAA'). Direct measurement of AN (concn. 0-800 mM) effect on NAA (215 μM) dissociation as indexed by change in solution pH revealed no significant effect, with a pH change from 4.19 to 4.05. This change is not sufficient to account for the observed enhancement. When 14C-NAA, buffered (20 mM sodium citrate) at pH 3.2, 4.2, 5.2, 6.2, was partitioned against chloroform, there was a marked increase in NAA partitioning into chloroform as pH was decreased. AN (8 mM) did not alter this partition behavior, also indicating no effect on NAA dissociation. However, in cuticle penetration studies, using a finite dose system with 14C-NAA buffered at pH 3.2, 4.2, 5.2, 6.2, and in the presence and absence of 8 mM AN, there was no marked or consistent pH or AN (-70 to + 232 % of no AN control) effect on penetration as indexed by initial slope (4-12 h) or penetration after 120 h. The possible effects of AN and buffer on penetration of 14C-NAA from the droplet deposit will be discussed.

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