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Articles 1 - 30 of 53
Full-Text Articles in Social and Behavioral Sciences
Model For Amorphous Aggregation Processes, Samual Stranks, Heath Ecroyd, Steve Van Sluyter, Elizabeth J. Waters, John A. Carver, Lorenz Von Smekal
Model For Amorphous Aggregation Processes, Samual Stranks, Heath Ecroyd, Steve Van Sluyter, Elizabeth J. Waters, John A. Carver, Lorenz Von Smekal
Heath Ecroyd
The amorphous aggregation of proteins is associated with many phenomena, ranging from the formation of protein wine haze to the development of cataract in the eye lens and the precipitation of recombinant proteins during their expression and purification. While much literature exists describing models for linear protein aggregation, such as amyloid fibril formation, there are few reports of models which address amorphous aggregation. Here, we propose a model to describe the amorphous aggregation of proteins which is also more widely applicable to other situations where a similar process occurs, such as in the formation of colloids and nanoclusters. As first …
Endogenous Redox Activity In Mouse Spermatozoa And Its Role In Regulating The Tyrosine Phosphorylation Events Associated With Sperm Capacitation, Heath W. Ecroyd, Russell C. Jones, Robert J. Aitken
Endogenous Redox Activity In Mouse Spermatozoa And Its Role In Regulating The Tyrosine Phosphorylation Events Associated With Sperm Capacitation, Heath W. Ecroyd, Russell C. Jones, Robert J. Aitken
Heath Ecroyd
We investigated the role of endogenous redox activity in regulating the signal transduction pathway leading to tyrosine phosphorylation in mouse spermatozoa. Endogenous redox activity was monitored using a luminol-peroxidase chemiluminescent probe. Chemiluminescence increased in spermatozoa that were actively undergoing cAMP-mediated tyrosine phosphorylation events associated with capacitation and was inhibited in a dose-dependent manner by addition of catalase or diphenylene iodonium, both of which also inhibited tyrosine phosphorylation within the cell at points downstream of cAMP. Excluding bicarbonate from the incubation medium reduced the redox activity of sperm by 80-90% and dramatically reduced tyrosine phosphorylation. This study provides the first evidence …
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 …
Tyrosine Phosphorylation Of Hsp-90 During Mammalian Sperm Capacitation, Heath Ecroyd, Russell Jones, Robert Aitken
Tyrosine Phosphorylation Of Hsp-90 During Mammalian Sperm Capacitation, Heath Ecroyd, Russell Jones, Robert Aitken
Heath Ecroyd
The process of sperm capacitation is correlated with activation of a signal transduction pathway leading to protein tyrosine phosphorylation. Whereas phosphotyrosine expression is an essential prerequisite for fertilization, the proteins that are phosphorylated during capacitation have not yet been identified. In the present study, we observed that a major target of this signaling pathway is the molecular chaperone protein, heat shock protein (HSP)-86, a member of the HSP-90 family of HSPs. We used cross-immunoprecipitation experiments to confirm the tyrosine phosphorylation of HSP-86, a process that is not inhibited by the ansamycin antibiotic, geldanamycin. The general significance of these findings was …
Dissociation From The Oligomeric State Is The Rate-Limiting Step In Fibril Formation By Kappa-Casein, Heath Ecroyd, Tomas Koudelka, David Thorn, Danielle Williams, Glyn Devlin, Peter Hoffmann, John Carver
Dissociation From The Oligomeric State Is The Rate-Limiting Step In Fibril Formation By Kappa-Casein, Heath Ecroyd, Tomas Koudelka, David Thorn, Danielle Williams, Glyn Devlin, Peter Hoffmann, John Carver
Heath Ecroyd
Amyloid fibrils are aggregated and precipitated forms of protein in which the protein exists in highly ordered, long, unbranching threadlike formations that are stable and resistant to degradation by proteases. Fibril formation is an ordered process that typically involves the unfolding of a protein to partially folded states that subsequently interact and aggregate through a nucleation-dependent mechanism. Here we report on studies investigating the molecular basis of the inherent propensity of the milk protein, kappa-casein, to form amyloid fibrils. Using reduced and carboxymethylated kappa-casein ( RCM kappa-CN), we show that fibril formation is accompanied by a characteristic increase in thioflavin …
An Epididymal Form Of Cauxin, A Carboxylesterase-Like Enzyme, Is Present And Active In Mammalian Male Reproductive Fluids, Heath W. Ecroyd, Maya Belghazi, Jl Dacheux, M Miyazaki, T Yamashita, Jl Gatti
An Epididymal Form Of Cauxin, A Carboxylesterase-Like Enzyme, Is Present And Active In Mammalian Male Reproductive Fluids, Heath W. Ecroyd, Maya Belghazi, Jl Dacheux, M Miyazaki, T Yamashita, Jl Gatti
Heath Ecroyd
Mass spectrometric analysis of a prion protein (PrP)-containing complex isolated from ram cauda epididymal fluid revealed a protein that showed homology to a carboxylesterase-like protein previously identified in cat urine (cauxin). Using anticauxin antibodies, immunoreactive bands were detected in corpus and cauda epididymal fluid from all mammals tested (ram, boar, mouse, and cat). In the ram, the protein was also present in seminal fluid but not found to be associated with sperm. The bands reacting with the anti-cauxin antibody coincided with those having esterase activity in a zymographic assay and its levels paralleled the esterase activity of native epididymal fluids. …
The Effect Of Small Molecules In Modulating The Chaperone Activity Of Alpha B-Crystallin Against Ordered And Disordered Protein Aggregation, Heath Ecroyd, John Carver
The Effect Of Small Molecules In Modulating The Chaperone Activity Of Alpha B-Crystallin Against Ordered And Disordered Protein Aggregation, Heath Ecroyd, John Carver
Heath Ecroyd
Protein aggregation can proceed via disordered or ordered mechanisms, with the latter being associated with amyloid fibril formation, which has been linked to a number of debilitating conditions including Alzheimer's, Parkinson's and Creutzfeldt-Jakob diseases. Small heat-shock proteins (sHsps), such as alpha B-crystallin, act as chaperones to prevent protein aggregation and are thought to play a key role in the prevention of protein-misfolding diseases. In this study, we have explored the potential for small molecules such as arginine and guanidine to affect the chaperone activity of alpha B-crystallin against disordered (amorphous) and ordered (amyloid fibril) forms of protein aggregation. The effect …
The Interaction Of Unfolding Α-Lactalbumin And Malate Dehydrogenase With The Molecular Chaperone Αb-Crystallin: A Light And X-Ray Scattering Investigation, J W. Regini, Heath Ecroyd, Sarah Meehan, Kristen Bremmell, Matthew J. Clarke, Donna Lammie, Tim Wess, John A. Carver
The Interaction Of Unfolding Α-Lactalbumin And Malate Dehydrogenase With The Molecular Chaperone Αb-Crystallin: A Light And X-Ray Scattering Investigation, J W. Regini, Heath Ecroyd, Sarah Meehan, Kristen Bremmell, Matthew J. Clarke, Donna Lammie, Tim Wess, John A. Carver
Heath Ecroyd
Purpose: The molecular chaperone αB-crystallin is found in high concentrations in the lens and is present in all major body tissues. Its structure and the mechanism by which it protects its target protein from aggregating and precipitating are not known. Methods: Dynamic light scattering and X-ray solution scattering techniques were used to investigate structural features of the αB-crystallin oligomer when complexed with target proteins under mild stress conditions, i.e., reduction of α- lactalbumin at 37 °C and malate dehydrogenase when heated at 42 °C. In this investigation, the size, shape and particle distribution of the complexes were determined in real-time …
Analysis Of The Mechanism By Which Calcium Negatively Regulates The Tyrosine Phosphorylation Cascade Associated With Sperm Capacitation, Mark Baker, Louise Hethrington, Heath Ecroyd, Shaun Roman, Robert Aitken
Analysis Of The Mechanism By Which Calcium Negatively Regulates The Tyrosine Phosphorylation Cascade Associated With Sperm Capacitation, Mark Baker, Louise Hethrington, Heath Ecroyd, Shaun Roman, Robert Aitken
Heath Ecroyd
The capacitation of mammalian spermatozoa involves the activation of a cAMP-mediated signal transduction pathway that drives tyrosine phosphorylation via mechanisms that are unique to this cell type. Controversy surrounds the impact of extracellular calcium on this process, with positive and negative effects being recorded in independent publications. We clearly demonstrate that the presence of calcium in the external medium decreases tyrosine phosphorylation in both human and mouse spermatozoa. Under these conditions, a rise in intracellular pH was recorded, however, this event was not responsible for the observed changes in phosphotyrosine expression. Rather, the impact of calcium on tyrosine phosphorylation in …
(-)-Epigallocatechin-3-Gallate (Egcg) Maintains K-Casein In Its Pre-Fibrillar State Without Redirecting Its Aggregation Pathway, Sean A. Hudson, Heath Ecroyd, Francis C. Dehle, Ian F. Musgrave, John Carver
(-)-Epigallocatechin-3-Gallate (Egcg) Maintains K-Casein In Its Pre-Fibrillar State Without Redirecting Its Aggregation Pathway, Sean A. Hudson, Heath Ecroyd, Francis C. Dehle, Ian F. Musgrave, John Carver
Heath Ecroyd
The polyphenol (-)-epigallocatechin-3-gallate (EGCG) has recently attracted much research interest in the field of protein-misfolding diseases because of its potent anti-amyloid activity against amyloid-beta, alpha-synuclein and huntingtin, the amyloid-fibril-forming proteins involved in Alzheimer's, Parkinson's and Huntington's diseases, respectively. EGCG redirects the aggregation of these polypeptides to a disordered off-folding pathway that results in the formation of non-toxic amorphous aggregates. whether this anti-fibril activity is specific to these disease-related target proteins or ismore generic remains to be established. In addition, the mechanism by which EGCG exerts its effects, as with all anti-amyloidogenic polyphenols, remains unclear. To address these aspects, we have …
The Two Faced Nature Of Milk Casein Proteins: Amyloid Fibril Formation And Chaperone-Like Activity, David Thorn, Heath Ecroyd, John Carver
The Two Faced Nature Of Milk Casein Proteins: Amyloid Fibril Formation And Chaperone-Like Activity, David Thorn, Heath Ecroyd, John Carver
Heath Ecroyd
Molecular chaperones are a diverse group of proteins that stabilise partially folded target proteins to prevent their misfolding, aggregation and potential precipitation under conditions of cellular stress, e.g. elevated temperature. Protein aggregation, particularly the formation of highly ordered protein aggregates termed amyloid fibrils, is of considerable research interest because of its intimate association with a wide range of debilitating diseases, including Alzheimer's, Parkinson's and Huntington's diseases and type II diabetes. In this review, we discuss the ability of the milk casein proteins to act in a chaperone-like manner. This property is of biological importance since at least two of the …
Mimicking Phosphorylation Of Alphab-Crystallin Affects Its Chaperone Activity, Heath W. Ecroyd, Sarah Meehan, J Horwitz, Andrew Aquilina, J L Benesch, C V Robinson, Cait Macphee, John Carver
Mimicking Phosphorylation Of Alphab-Crystallin Affects Its Chaperone Activity, Heath W. Ecroyd, Sarah Meehan, J Horwitz, Andrew Aquilina, J L Benesch, C V Robinson, Cait Macphee, John Carver
Heath Ecroyd
No abstract provided.
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 …
Unraveling The Mysteries Of Protein Folding And Misfolding, Heath Ecroyd, John A. Carver
Unraveling The Mysteries Of Protein Folding And Misfolding, Heath Ecroyd, John A. Carver
Heath Ecroyd
This mini-review focuses on the processes and consequences of protein folding and misfolding. The latter process often leads to protein aggregation and precipitation with the aggregates adopting either highly ordered (amyloid fibril) or disordered (amorphous) forms. In particular, the amyloid fibril is discussed because this form has gained considerable notoriety due to its close links to a variety of debilitating diseases including Alzheimer's, Parkinson's, Huntington's, and Creutzfeldt-Jakob diseases, and type-II diabetes. In each of these diseases a different protein forms fibrils, yet the fibrils formed have a very similar structure. The mechanism by which fibrils form, fibril structure, and the …
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, …
Amyloid Fibril Formation By Bovine Milk Alpha(S2)-Casein Occurs Under Physiological Conditions Yet Is Prevented By Its Natural Counterpart, Alpha(S1)-Casein, David Thorn, Heath Ecroyd, M Sunde, Stephen Poon, John Carver
Amyloid Fibril Formation By Bovine Milk Alpha(S2)-Casein Occurs Under Physiological Conditions Yet Is Prevented By Its Natural Counterpart, Alpha(S1)-Casein, David Thorn, Heath Ecroyd, M Sunde, Stephen Poon, John Carver
Heath Ecroyd
The calcified proteinaceous deposits, or corpora amylacea, of bovine mammary tissue often comprise a network of amyloid fibrils, the origins of which have not been fully elucidated. Here, we demonstrate by transmission electron microscopy, dye binding assays, and X-ray fiber diffraction that bovine milk alpha(s2)-casein, a protein synthesized and secreted by mammary epithelial cells, readily forms fibrils in vitro. As a component of whole alpha(s)-casein, alpha(s2)-casein was separated from alpha(s1)-casein under nonreducing conditions via cation-exchange chromatography. Upon incubation at neutral pH and 37 degrees C, the spherical particles typical of alpha(s2)-casein rapidly converted to twisted, ribbon-like fibrils similar to 12 …
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 Epididymal Soluble Prion Protein Forms A High-Molecular-Mass Complex In Association With Hydrophobic Proteins, Heath W. Ecroyd, Maya Belghazi, Jean-Louis Dacheux, Jean-Luc Gatti
The Epididymal Soluble Prion Protein Forms A High-Molecular-Mass Complex In Association With Hydrophobic Proteins, Heath W. Ecroyd, Maya Belghazi, Jean-Louis Dacheux, Jean-Luc Gatti
Heath Ecroyd
We have shown previously that a 'soluble' form of PrP (prion protein), not associated with membranous vesicles, exists in the male reproductive fluid [Ecroyd, Sarradin, Dacheux and Gatti (2004) Biol. Reprod. 71, 993-1001]. Attempts to purify this 'soluble' PrP indicated that it behaves like a high-molecular-mass complex of more than 350 kDa and always co-purified with the same set of proteins. The main associated proteins were sequenced by MS and were found to match to clusterin (apolipoprotein J), BPI (bacterial permeability-increasing protein), carboxylesterase-like urinary excreted protein (cauxin), beta-mannosidase and beta-galactosidase. Immunoblotting and enzymatic assay confirmed the presence of clusterin and …
Compartmentalization Of Prion Isoforms Within The Reproductive Tract Of The Ram, Heath W. Ecroyd, Pierre Sarradin, Jean-Louis Dacheux, Jean-Luc Gatti
Compartmentalization Of Prion Isoforms Within The Reproductive Tract Of The Ram, Heath W. Ecroyd, Pierre Sarradin, Jean-Louis Dacheux, Jean-Luc Gatti
Heath Ecroyd
Cellular prion protein (Prp(C)) is a glycoprotein usually associated with membranes via its glycosylphosphatidylinositol (GPI) anchor. The trans-conformational form of this protein (Prp(SC)) is the suggested agent responsible for transmissible neurodegenerative spongiform encephalopathies. This protein has been shown on sperm and in the reproductive fluids of males. Antibodies directed against the C-terminal sequence near the GPI-anchor site, an N-terminal sequence, and against the whole protein showed that the Prp isoforms were compartmentalized within the reproductive tract of the ram. Immunoblotting with the three antibodies showed that the complete protein and both N- and C-terminally truncated and glycosylated isoforms are present …
Protective Interactions Of Dairy Peptides With Fibril Structures And Relevance To Alzheimer's Disease, Louise Bennett, Williams Roderick, Heath Ecroyd, Yanqin Liu, Sunanda Sudharmarajan, John Carver
Protective Interactions Of Dairy Peptides With Fibril Structures And Relevance To Alzheimer's Disease, Louise Bennett, Williams Roderick, Heath Ecroyd, Yanqin Liu, Sunanda Sudharmarajan, John Carver
Heath Ecroyd
Selected dairy caseins have been shown to have capacity for chaperone-like regulation of folding pathways of other caseins, specifically in preventing development of fibrillar aggregates of beta sheet structure. An assay based on fibril formation by reduced and carboxymethylated-kappa casein (RCM-kCn) was thus used to screen for anti-fibril activity among a selection of dairy protein hydrolysates, in order to discover peptides with possible anti-fibril, chaperone activity. From the selection of eight dairy hydrolysates based on different dairy protein fractions, two of the hydrolysates of whey protein exhibited superior anti-fibril bioactivity against RCM-kCn and amyloid beta (Aβ), the peptide associated with …
Testicular Descent, Sperm Maturation And Capacitation. Lessons From Our Most Distant Relatives, The Monotremes, Russell Jones, Heath Ecroyd, Jean-Louis Dacheux, Brett Nixon
Testicular Descent, Sperm Maturation And Capacitation. Lessons From Our Most Distant Relatives, The Monotremes, Russell Jones, Heath Ecroyd, Jean-Louis Dacheux, Brett Nixon
Heath Ecroyd
The present review examines whether monotremes may help to resolve three questions relating to sperm production in mammals: why the testes descend into a scrotum in most mammals, why spermatozoa are infertile when they leave the testes and require a period of maturation in the specific milieu provided by the epididymides, and why ejaculated spermatozoa cannot immediately fertilise an ovum until they undergo capacitation within the female reproductive tract. Comparisons of monotremes with other mammals indicate that there is a need for considerable work on monotremes. It is hypothesised that testicular descent should be related to epididymal differentiation. Spermatozoa and …
The Development Of Signal Transduction Pathways During Epididymal Maturation Is Calcium Dependent, Heath W. Ecroyd, Kelly Asquith, Russell C. Jones, Robert J. Aitken
The Development Of Signal Transduction Pathways During Epididymal Maturation Is Calcium Dependent, Heath W. Ecroyd, Kelly Asquith, Russell C. Jones, Robert J. Aitken
Heath Ecroyd
Capacitation has been correlated with the activation of a cAMP-PKA-dependent signaling pathway leading to protein tyrosine phosphorylation. The ability to exhibit this response to cAMP matures during epididymal maturation in concert with the ability of the sperrnatozoa to capacitate. In this study, we have addressed the mechanisms by which spermatozoa gain the potential to activate this signaling pathway during epididymal maturation. In a modified Tyrode's medium containing 1.7 mM calcium, caput spermatozoa had significantly higher [Ca2+](i) than caudal cells and could not tyrosine phosphorylate in response to cAMP. However, in calcium-depleted medium both caput and caudal cells could exhibit a …
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 …
Identification Of Abundant Alkyl Ether Glycerophospholipids In The Human Lens By Tandem Mass Spectrometry Techniques, Roger J. Truscott, Jane Deeley, Todd W. Mitchell, Michael Thomas, Stephen J. Blanksby
Identification Of Abundant Alkyl Ether Glycerophospholipids In The Human Lens By Tandem Mass Spectrometry Techniques, Roger J. Truscott, Jane Deeley, Todd W. Mitchell, Michael Thomas, Stephen J. Blanksby
Stephen Blanksby
Previous studies have shown that the human lens contains glycerophospholipids with ether linkages. These lipids differ from conventional glycerophospholipids in that the sn-1 substituent is attached to the glycerol backbone via an 1-O-alkyl or an 1-O-alk-1'-enyl ether rather than an ester bond. The present investigation employed a combination of collision-induced dissociation (CID) and ozone-induced dissociation (OzID) to unambiguously distinguish such 1-O-alkyl and 1-O-alk-1'-enyl ethers. Using these methodologies the human lens was found to contain several abundant 1-O-alkyl glycerophos-phoethanolamines, including GPEtn(16:0e/9Z-18:1), GPEtn(11Z-18:1e/9Z-18:1), and GPEtn(18:0e/9Z-18:1), as well as a related series of unusual 1-O-alkyl glycerophosphoserines, including GPSer(16:0e/9Z-18:1), GPSer(11Z-18:1e/9Z-18:1), GPSer(18:0e/9Z-18:1) that to our …
Detection And Quantification Of Tear Phospholipids And Cholesterol In Contact Lens Deposits: The Effect Of Contact Lens Material And Lens Care Solution, Jennifer Saville, Zhenjun Zhao, Mark D.P. Willcox, Stephen J. Blanksby, Todd W. Mitchell
Detection And Quantification Of Tear Phospholipids And Cholesterol In Contact Lens Deposits: The Effect Of Contact Lens Material And Lens Care Solution, Jennifer Saville, Zhenjun Zhao, Mark D.P. Willcox, Stephen J. Blanksby, Todd W. Mitchell
Stephen Blanksby
PURPOSE. To examine the deposition of tear phospholipids and cholesterol onto worn contact lenses and the effect of lens material and lens care solution. METHODS. Lipids were extracted from tears and worn contact lenses using 2: 1 chloroform: methanol and the extract washed with aqueous ammonium acetate, before analysis by electrospray ionization tandem mass spectrometry (ESI-MS/MS). RESULTS. Twenty-three molecular lipids from the sphingomyelin (SM) and phosphatidylcholine (PC) classes were detected in tears, with total concentrations of each class determined to be 5 +/- 1 pmol/mu L (similar to 3.8 mu g/mL) and 6 +/- 1 pmol/mu L (similar to 4.6 …
Berberine-Inf55 (5-Nitro-2-Phenylindole) Hybrid Antimicrobials: Effects Of Varying The Relative Orientation Of The Berberine And Inf55 Components, Danuta Tomkiewicz, Gabriele Casadei, Jonah Larkins-Ford, Terence I. Moy, James A. Garner, John B. Bremner, Frederik M. Ausubel, Kim Lewis, Michael J. Kelso
Berberine-Inf55 (5-Nitro-2-Phenylindole) Hybrid Antimicrobials: Effects Of Varying The Relative Orientation Of The Berberine And Inf55 Components, Danuta Tomkiewicz, Gabriele Casadei, Jonah Larkins-Ford, Terence I. Moy, James A. Garner, John B. Bremner, Frederik M. Ausubel, Kim Lewis, Michael J. Kelso
Kim Lewis
Hybrid antimicrobials containing an antibacterial linked to a multidrug resistance (MDR) pump inhibitor make up a promising new class of agents for countering efflux-mediated bacterial drug resistance. This study explores the effects of varying the relative orientation of the antibacterial and efflux pump inhibitor components in three isomeric hybrids (SS14, SS14-M, and SS14-P) which link the antibacterial alkaloid and known substrate for the NorA MDR pump berberine to different positions on INF55 (5-nitro-2-phenylindole), an inhibitor of NorA. The MICs for all three hybrids against wild-type, NorA-knockout, and NorA-overexpressing Staphylococcus aureus cells were found to be similar (9.4 to 40.2 mu …
Synthesis Of 3-Halo-2,5-Disubstituted Furans Via Cux Mediated Cyclization-Halogenation Reactions, Arife Yazici, Stephen G. Pyne
Synthesis Of 3-Halo-2,5-Disubstituted Furans Via Cux Mediated Cyclization-Halogenation Reactions, Arife Yazici, Stephen G. Pyne
Faculty of Science - Papers (Archive)
The Cu(I) halide (X = I, Br, Cl) mediated reactions of Cbz-protected cis-2-phenylethenyl-3-hydroxypyrrolidine gave novel 3-halo-2,5-trisubstituted furans in good yields, via a cyclization-halogenation, ring-opening reaction sequence. In contrast, the reactions with CuCN gave mainly the corresponding 3-cyanofuro[3,2-b]pyrrole formed from a cyclization-cyanation reaction.
An Unusually Flexible Expanded Hexaamine Cage And Its Cuii Complexes: Variable Coordination Modes And Incomplete Encapsulation, C-J Qin, Lloyd James, Jy D. Chartres, Leighton J. Alcock, Kimberley J. Davis, Anthony C. Willis, Alan M. Sargeson, Paul V. Bernhardt, Stephen F. Ralph
An Unusually Flexible Expanded Hexaamine Cage And Its Cuii Complexes: Variable Coordination Modes And Incomplete Encapsulation, C-J Qin, Lloyd James, Jy D. Chartres, Leighton J. Alcock, Kimberley J. Davis, Anthony C. Willis, Alan M. Sargeson, Paul V. Bernhardt, Stephen F. Ralph
Faculty of Science - Papers (Archive)
The bicyclic hexaamine "cage" ligand Me 8tricosaneN 6 (1,5,5,9,13,13,20,20-octamethyl-3,7,11,15,18, 22-hexaazabicyclo[7.7.7]tricosane) is capable of encapsulating octahedral metal ions, yet its expanded cavity allows the complexed metal to adopt a variety of geometries comprising either hexadentate or pentadentate coordination of the ligand. When complexed to Cu II the lability of the metal results in a dynamic equilibrium in solution between hexadentate- and pentadentate- coordinated complexes of Me 8tricosaneN 6. Both [Cu(Me 8tricosaneN 6)](ClO 4) 2 (6-coordinate) and [Cu(Me 8tricosaneN 6)](S 2O 6) (5-coordinate) have been characterized structurally. In weak acid (pH 1) a singly protonated complex [Cu(HMe 8tricosaneN 6)] 3+ has been …
Synthesis And Structural Characterization Of 1-[2-(5-Nitro-1h-Indol-2-Yl)Phenyl]Methylpyridinium Chloride, John B. Bremner, Siritron Samosorn, Brian W. Skelton, Allan White
Synthesis And Structural Characterization Of 1-[2-(5-Nitro-1h-Indol-2-Yl)Phenyl]Methylpyridinium Chloride, John B. Bremner, Siritron Samosorn, Brian W. Skelton, Allan White
Faculty of Science - Papers (Archive)
In the course of studies on hybrid antibacterials incorporating 2-aryl-5-nitro-1Hindolemoieties as potential bacterial NorA efflux pump inhibitors, the compound 1-[2-(5-nitro-1H-indol-2-yl)phenyl]methylpyridinium chloride (2) was synthesized and structurallycharacterized. This pyridinium chloride salt crystallized in the monoclinic space groupP21/c with the following unit cell dimensions: a 10.274(3) A, b 13.101(4) A, c 13.439(4)A, B 107.702(7)deg, V 1723.2(9) A3, Z (f.u.) = 4; R1 = 0.048, and wR2 = 0.13. Of interest inthe single crystal X-ray structure is the (intramolecular) disposition of the pyridinium planeover the indole heterocyclic residue [interplanar dihedral angle 17.91(4)deg].
Nanoesi Mass Spectrometry Of Rubisco And Rubisco Activase Structures And Their Interactions With Nucleotides And Sugar Phosphates, Michelle Blayney, Spencer M. Whitney, Jennifer L. Beck
Nanoesi Mass Spectrometry Of Rubisco And Rubisco Activase Structures And Their Interactions With Nucleotides And Sugar Phosphates, Michelle Blayney, Spencer M. Whitney, Jennifer L. Beck
Faculty of Science - Papers (Archive)
Ribulose bisphosphate carboxylase/oxygenase (Rubisco) is the protein that is responsible for the fixation of carbon dioxide in photosynthesis. Inhibitory sugar phosphate molecules, which can include its substrate ribulose-1,5- bisphosphate (RuBP), can bind to Rubisco catalytic sites and inhibit catalysis. These are removed by interaction with Rubisco activase (RA) via an ATP hydrolytic reaction. Here we show the first nanoESI mass spectra of the hexadecameric Rubisco and of RA from a higher plant (tobacco). The spectra of recombinant, purified RA revealed polydispersity in its oligomeric forms (up to hexamer) and that ADP was bound. ADP was removed by dialysis against a …