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Full-Text Articles in Physical Sciences and Mathematics
Carboxymethylated-K-Casein: A Convenient Tool For The Identification Of Polyphenolic Inhibitors Of Amyloid Fibril Formation, John A. Carver, Peter J. Duggan, Heath Ecroyd, Yanqin Liu, Adam G. Meyer, C E. Tranberg
Carboxymethylated-K-Casein: A Convenient Tool For The Identification Of Polyphenolic Inhibitors Of Amyloid Fibril Formation, John A. Carver, Peter J. Duggan, Heath Ecroyd, Yanqin Liu, Adam G. Meyer, C E. Tranberg
Heath Ecroyd
Reduced and carboxymethylated-κ-casein (RCM-κ-CN) is a milk-derived amyloidogenic protein that readily undergoes nucleation-dependent aggregation and amyloid fibril formation via a similar pathway to disease-specific amyloidogenic peptides like amyloid beta (Aβ), which is associated with Alzheimer’s disease. In this study, a series of flavonoids, many known to be inhibitors of Aβ fibril formation, were screened for their ability to inhibit RCM-κ-CN fibrilisation, and the results were compared with literature data on Aβ inhibition. Flavonoids that had a high degree of hydroxylation and molecular planarity gave good inhibition of RCM-κ-CN fibril formation. IC50 values were between 10- and 200-fold higher with RCM-κ-CN …
The Dissociated Form Of Kappa-Casein Is The Precursor To Its Amyloid Fibril Formation, Heath Ecroyd, David Thorn, Yanqin Liu, John Carver
The Dissociated Form Of Kappa-Casein Is The Precursor To Its Amyloid Fibril Formation, Heath Ecroyd, David Thorn, Yanqin Liu, John Carver
Heath Ecroyd
Bovine milk kappa-casein forms a self-associating oligomeric micelle-like species, in equilibrium with dissociated forms. In its native form, intra- and inter-molecular disulfide bonds lead to the formation of multimeric species ranging from monomers to decamers. When incubated under conditions of physiological pH and temperature, both reduced and non-reduced kappa-casein form highly structured beta-sheet amyloid fibrils. We investigated whether the precursor to kappa-casein fibril formation is a dissociated state of the protein or its oligomeric micelle-like form. We show that reduced kappa-casein is capable of forming fibrils well below its critical micelle concentration, i.e. at concentrations where only dissociated forms of …
The Thioflavin T Fluorescence Assay For Amyloid Fibril Detection Can Be Biased By The Presence Of Exogenous Compounds, Sean A. Hudson, Heath Ecroyd, Tak W. Kee, John A. Carver
The Thioflavin T Fluorescence Assay For Amyloid Fibril Detection Can Be Biased By The Presence Of Exogenous Compounds, Sean A. Hudson, Heath Ecroyd, Tak W. Kee, John A. Carver
Heath Ecroyd
Thioflavin T (ThT) dye fluorescence is used regularly to quantify the formation and inhibition of amyloid fibrils in the presence of anti-amyloidogenic compounds such as polyphenols. However, in this study, it was shown, using three polyphenolics (curcumin, quercetin and resveratrol), that ThT fluorescence should be used with caution in the presence of such exogenous compounds. The strong absorptive and fluorescent properties of quercetin and curcumin were found to significantly bias the ThT fluorescence readings in both in situ real-time ThT assays and single time-point dilution ThT-type assays. The presence of curcumin at concentrations as low as 0.01 and 1 uM …
Crystallin Proteins And Amyloid Fibrils, Heath Ecroyd, John A. Carver
Crystallin Proteins And Amyloid Fibrils, Heath Ecroyd, John A. Carver
Heath Ecroyd
Improper protein folding (misfolding) can lead to the formation of disordered (amorphous) or ordered (amyloid fibril) aggregates. The major lens protein, alpha-crystallin, is a member of the small heat-shock protein (sHsp) family of intracellular molecular chaperone proteins that prevent protein aggregation. Whilst the chaperone activity of sHsps against amorphously aggregating proteins has been well studied, its action against fibril-forming proteins has received less attention despite the presence of sHsps in deposits found in fibril-associated diseases (e.g. Alzheimer's and Parkinson's). In this review, the literature on the interaction of alpha B-crystallin and other sHsps with fibril-forming proteins is summarized. In particular, …
Alphab-Crystallin Inhibits The Cell Toxicity Associated With Amyloid Fibril Formation By Kappa-Casein And The Amyloid-Beta Peptide, Francis C. Dehle, Heath Ecroyd, Ian F. Musgrave, John A. Carver
Alphab-Crystallin Inhibits The Cell Toxicity Associated With Amyloid Fibril Formation By Kappa-Casein And The Amyloid-Beta Peptide, Francis C. Dehle, Heath Ecroyd, Ian F. Musgrave, John A. Carver
Heath Ecroyd
Amyloid fibril formation is associated with diseases such as Alzheimer’s, Parkinson’s, and prion diseases. Inhibition of amyloid fibril formation by molecular chaperone proteins, such as the small heat-shock protein αB-crystallin, may play a protective role in preventing the toxicity associated with this form of protein misfolding. Reduced and carboxymethylated κ-casein (RCMκ-CN), a protein derived from milk, readily and reproducibly forms fibrils at physiological temperature and pH. We investigated the toxicity of fibril formation by RCMκ-CN using neuronal model PC12 cells and determined whether the inhibition of fibril formation altered its cell toxicity. To resolve ambiguities in the literature, we also …
The Interaction Of Alphab-Crystallin With Mature Alpha-Synuclein Amyloid Fibrils Inhibits Their Elongation, Christopher A. Waudby, Tuomas P. J Knowles, Glyn L. Devlin, Jeremy N. Skepper, Heath Ecroyd, John A. Carver, Mark E. Welland, John Christodoulou, Christopher M. Dobson, Sarah Meehan
The Interaction Of Alphab-Crystallin With Mature Alpha-Synuclein Amyloid Fibrils Inhibits Their Elongation, Christopher A. Waudby, Tuomas P. J Knowles, Glyn L. Devlin, Jeremy N. Skepper, Heath Ecroyd, John A. Carver, Mark E. Welland, John Christodoulou, Christopher M. Dobson, Sarah Meehan
Heath Ecroyd
alphaB-Crystallin is a small heat-shock protein (sHsp) that is colocalized with alpha-synuclein (alphaSyn) in Lewy bodies—the pathological hallmarks of Parkinson's disease—and is an inhibitor of alphaSyn amyloid fibril formation in an ATP-independent manner in vitro. We have investigated the mechanism underlying the inhibitory action of sHsps, and here we establish, by means of a variety of biophysical techniques including immunogold labeling and nuclear magnetic resonance spectroscopy, that alphaB-crystallin interacts with alphaSyn, binding along the length of mature amyloid fibrils. By measurement of seeded fibril elongation kinetics, both in solution and on a surface using a quartz crystal microbalance, this binding …