48 results found
Rehal R, Gaffney PRJ, Hubbard ATM, et al., 2019, The pH-dependence of lipid-mediated antimicrobial peptide resistance in a model staphylococcal plasma membrane: A two-for-one mechanism of epithelial defence circumvention., Eur J Pharm Sci, Vol: 128, Pages: 43-53
The mechanisms of membrane defence by lysylphosphatidylglycerol (LPG), were investigated using synthetic biomimetic mono- and bilayer models of methicillin resistant S. aureus ST239 TW, based on its lipid composition in both pH 7.4 (28% LPG) and pH 5.5 (51% LPG) cultures. These models incorporated a stable synthetic analogue of LPG (3adLPG) to facilitate long-duration biophysical studies, which were previously limited by the lability native LPG. Both increased 3adLPG content and full headgroup ionization at pH 5.5, increased bilayer order and dampened overall charge, via the formation of neutral ion pairs with anionic lipids. Ion pair formation in air/liquid interface lipid monolayers elicited a significant condensing effect, which correlated with the inhibition of subphase-injected magainin 2 F5W partitioning. In fluid phase lipid vesicles, increasing the proportion of 3adLPG from 28 to 51 mol% completely inhibited the adoption of the membrane-active α‑helical conformation of the peptide, without the need for full headgroup ionization. Neutron reflectivity measurements performed on biomimetic PG/3adLPG fluid floating bilayers, showed a significant ordering effect of mild acidity on a bilayer containing 30 mol% 3adLPG, whilst peptide binding/partitioning was only fully inhibited in a bilayer with 55 mol% 3adLPG at pH 5.5. These findings are discussed with respect to the roles of LPG in resistance to human epithelial defences in S. aureus and the continued evolution of this opportunistic pathogen's virulence.
Dong R, Liu R, Gaffney PRJ, et al., 2019, Author Correction: Sequence-defined multifunctional polyethers via liquid-phase synthesis with molecular sieving, Nature Chemistry, Vol: 11, Pages: 184-184, ISSN: 1755-4330
Correction to: Nature Chemistry https://doi.org/10.1038/s41557-018-0169-6, published online 3 December 2018.
Dong R, Liu R, Gaffney P, et al., 2018, Sequence-defined multifunctional polyethers via liquid-phase synthesis with molecular sieving, Nature Chemistry, Vol: 11, Pages: 136-145, ISSN: 1755-4330
Synthetic chemists have devoted tremendous effort towards the production of precision synthetic polymers with defined sequences and specific functions. However, the creation of a general technology that enables precise control over monomer sequence, with efficient isolation of the target polymers, is highly challenging. Here, we report a robust strategy for the production of sequence-defined synthetic polymers through a combination of liquid-phase synthesis and selective molecular sieving. The polymer is assembled in solution with real-time monitoring to ensure couplings proceed to completion, on a three-armed star-shaped macromolecule to maximize efficiency during the molecular sieving process. This approach is applied to the construction of sequence-defined polyethers, with side-arms at precisely defined locations that can undergo site-selective modification after polymerization. Using this versatile strategy, we have introduced structural and functional diversity into sequence-defined polyethers, unlocking their potential for real-life applications in nanotechnology, healthcare and information storage.
Cook M, Gaffney P, Peeva L, et al., 2018, Roll-to-roll dip coating of three different PIMs for Organic Solvent Nanofiltration, Journal of Membrane Science, Vol: 558, Pages: 52-63, ISSN: 0376-7388
PIM-1, PIM-7, and PIM-8 composite membranes have been fabricated for Organic Solvent Nanofiltration (OSN) on two different support membranes. Both support membranes, PAN and crosslinked Ultem 1000, displayed pore sizes within the range of 20–25 nm as characterised by gas liquid porometry. PIM layers of < 500 nm thickness were formed from dip coating on a roll-to-roll pilot line. The resultant composite membranes exhibited typical MWCOs in the region of 500–800 g mol−1. The quality of coating obtained on the crosslinked Ultem 1000 support membrane was consistently higher for all three PIMs than that obtained on the PAN membrane. The PIM composite membranes coated on to crosslinked Ultem 1000 were stable in a wider range of solvents than those on the PAN support. OSN testing in a model system with isomeric alkane solutes verified that manipulated changes to the molecular architecture of the polymer backbone resulted in a higher separation factor between straight and branched alkane isomers.
Gaffney P, Livingston A, Chen R, et al., 2017, Defined Monomer Sequence Polymers, WO/2017/042583
Processes of preparing defined monomer sequence polymers are disclosed, in which a backbone portion of the polymer is first prepared by performing one or more sequential monomeric coupling reactions with intervening membrane diafiltration purification/isolation steps, followed by a step of decorating the backbone portion with one or more side chains at predetermined positions along its length. The process represents an improvement on prior art techniques, which impose limitations on the size of the side chains that may be present. Defined monomer sequence polymers that are obtainable by the processes are also disclosed.
Furse S, Brooks NJ, Woscholski R, et al., 2016, Pressure-dependent inverse bicontinuous cubic phase formation in a phosphatidylinositol 4-phosphate/phosphatidylcholine system, Chemical Data Collections, Vol: 3-4, Pages: 15-20, ISSN: 2405-8300
In this paper, we report the inositide-driven formation of an inverse bicontinuous cubic phase with space group Ia3d (QIIG, gyroid phase). The system under study consisted of distearoylphosphatidylinositol 4-phosphate (DSPIP) and dioleoylphosphatidylcholine at a molar ratio of 1:49, with a physiological concentration of magnesium ions at pH 7·4. The behaviour of the system was monitored as a function of temperature and pressure. The formation of the phase with Ia3d geometry was recorded repeatably at high pressure, and occurred more readily at higher temperatures. We conclude that the Ia3d phase formed is a thermodynamically stable structure, and that DSPIP is a potent source of membrane curvature that can drive the formation of mesophases with both 2- and 3D geometry.
Kim JF, Gaffney PRJ, Valtcheva IB, et al., 2016, Organic Solvent Nanofiltration (OSN): A New Technology Platform for Liquid-Phase Oligonucleotide Synthesis (LPOS), Organic Process Research and Development, Vol: 20, Pages: 1439-1452, ISSN: 1083-6160
Organic solvent nanofiltration (OSN) technology is a membrane process for molecular separation in harsh organic media. However, despite having well-documented potential applications, development hurdles have hindered the widespread uptake of OSN technology. One of the most promising areas of application is as an iterative synthesis platform, for instance for oligonucleotides or peptides, where a thorough purification step is required after each synthesis cycle, preferably in the same working solvent. In this work, we report a process development study for liquid-phase oligonucleotide synthesis (LPOS) using OSN technology. Oligonucleotide (oligo) based drugs are being advanced as a new generation of therapeutics functioning at the protein expression level. Currently, over 100 oligo based drugs are undergoing clinical trials, suggesting that it will soon be necessary to produce oligos at a scale of metric tons per year. However, there are as yet no synthesis platforms that can manufacture oligos at >10 kg batch scale. With the process developed here, we have successfully carried out eight iterative cycles of chain extension and synthesized 5-mer and 9-mer 2′-O-methyl oligoribonucleotide phosphorothioates, all in liquid phase media. This paper discusses the key challenges, both anticipated and unexpected, faced during development of this process and suggests solutions to reduce the development period. An economic analysis has been carried out, highlighting the potential competitiveness of the LPOS-OSN process and the necessity for a solvent recovery unit.
Gaffney PRJ, ces O, arduin A, 2015, Regulation of PLCβ2 by the electrostatic and mechanical properties of lipid bilayers, Scientific Reports, Vol: 5, ISSN: 2045-2322
Phosphoinositide-specific phospholipase C (PLC) is an important family of enzymes constituting a junction between phosphoinositide lipid signaling and the trans-membrane signal transduction processes that are crucial to many living cells. However, the regulatory mechanism of PLC is not yet understood in detail. To address this issue, activity studies were carried out using lipid vesicles in a model system that was specifically designed to study protein-protein and lipid-protein interactions in concert. Evidence was found for a direct interaction between PLC and the GTPases that mediate phospholipase activation. Furthermore, for the first time, the relationships between PLC activity and substrate presentation in lipid vesicles of various sizes, as well as lipid composition and membrane mechanical properties, were analyzed. PLC activity was found to depend upon the electrostatic potential and the stored curvature elastic stress of the lipid membranes.
Gaffney PRJ, Kim JF, Valtcheva IB, et al., 2015, Liquid-phase synthesis of 2′-methyl-RNA on a homostar support through organic-solvent nanofiltration, Chemistry-A European Journal, Vol: 21, Pages: 9535-9543, ISSN: 1521-3765
Due to the discovery of RNAi, oligonucleotides (oligos) have re-emerged as a major pharmaceutical target that may soon be required in ton quantities. However, it is questionable whether solid-phase oligo synthesis (SPOS) methods can provide a scalable synthesis. Liquid-phase oligo synthesis (LPOS) is intrinsically scalable and amenable to standard industrial batch synthesis techniques. However, most reported LPOS strategies rely upon at least one precipitation per chain extension cycle to separate the growing oligonucleotide from reaction debris. Precipitation can be difficult to develop and control on an industrial scale and, because many precipitations would be required to prepare a therapeutic oligonucleotide, we contend that this approach is not viable for large-scale industrial preparation. We are developing an LPOS synthetic strategy for 2′-methyl RNA phosphorothioate that is more amenable to standard batch production techniques, using organic solvent nanofiltration (OSN) as the critical scalable separation technology. We report the first LPOS-OSN preparation of a 2′-Me RNA phosphorothioate 9-mer, using commercial phosphoramidite monomers, and monitoring all reactions by HPLC, 31P NMR spectroscopy and MS.
Yau HC, Bayazit MK, Gaffney PRJ, et al., 2015, Synthesis and characterization of branched fullerene-terminated poly(ethylene glycol)s, POLYMER CHEMISTRY, Vol: 6, Pages: 1056-1065, ISSN: 1759-9954
Furse S, Mak L, Tate EW, et al., 2015, Synthesis of unsaturated phosphatidylinositol 4-phosphates and the effects of substrate unsaturation on SopB phosphatase activity, ORGANIC & BIOMOLECULAR CHEMISTRY, Vol: 13, Pages: 2001-2011, ISSN: 1477-0520
Szekely G, Schaepertoens M, Gaffney PRJ, et al., 2014, Beyond PEG2000: Synthesis and Functionalisation of Monodisperse PEGylated Homostars and Clickable Bivalent Polyethyleneglycols, CHEMISTRY-A EUROPEAN JOURNAL, Vol: 20, Pages: 10038-10051, ISSN: 0947-6539
Szekely G, Schaepertoens M, Gaffney PRJ, et al., 2014, Iterative synthesis of monodisperse PEG homostars and linear heterobifunctional PEG, POLYMER CHEMISTRY, Vol: 5, Pages: 694-697, ISSN: 1759-9954
Rosen SAJ, Gaffney PRJ, Gould I, 2012, Flipping inositol phosphates: A molecular dynamics approach to understanding the selectivity of protein kinase B, 11th International Biorelated Polymer Symposium / 243rd National Spring Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Rosen SAJ, Gaffney PRJ, Gould IR, 2012, Understanding the interactions of inositol phosphates with protein kinase B using long time-scale simulations, 11th International Biorelated Polymer Symposium / 243rd National Spring Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Rosen SAJ, Gaffney PRJ, Spiess B, et al., 2012, Understanding the relative affinity and specificity of the pleckstrin homology domain of protein kinase B for inositol phosphates, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 14, Pages: 929-936, ISSN: 1463-9076
Furse S, Brooks NJ, Seddon AM, et al., 2012, Lipid membrane curvature induced by distearoyl phosphatidylinositol 4-phosphate, Soft Matter
Furse S, Brooks NJ, Seddon AM, et al., 2012, Lipid membrane curvature induced by distearoyl phosphatidylinositol 4-phosphate, Soft Matter, Vol: 8, Pages: 3090-3093
In this paper we present evidence that phosphatidylinositol 4-phosphate induces curvature in biological membranes. The phase behaviour of mixtures of distearoylphosphatidylinositol 4-phosphate (DSPIP) and dioleoylphosphatidylcholine (DOPC) as a function of pressure and temperature has been studied using small-angle X-ray scattering and in the presence of biologically relevant magnesium concentrations. Our results demonstrate that at physiologically relevant concentrations (2 mol%), DSPIP is capable of inducing the formation of the inverse hexagonal phase (HII) over a wide range of conditions. This result has implications for the structural role of phosphatidylinositol lipids in vivo.
Rosen SAJ, Gaffney PRJ, Gould IR, 2011, A theoretical investigation of inositol 1,3,4,5-tetrakisphosphate, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 13, Pages: 1070-1081, ISSN: 1463-9076
Swarbrick JM, Gaffney PRJ, 2010, Synthesis of 4-C-Alkyl Inositol 1,4,5-Trisphosphates and 1,3,4,5-Tetrakisphosphates, JOURNAL OF ORGANIC CHEMISTRY, Vol: 75, Pages: 4376-4386, ISSN: 0022-3263
Panchal N, Gaffney PRJ, 2009, Synthesis of unsaturated phosphatidylinositol 4,5-bisphosphate and analogues, ORGANIC & BIOMOLECULAR CHEMISTRY, Vol: 7, Pages: 4832-4841, ISSN: 1477-0520
Swarbrick JM, Cooper S, Bultynck G, et al., 2009, Regioselective deprotection of orthobenzoates for the synthesis of inositol phosphates, ORGANIC & BIOMOLECULAR CHEMISTRY, Vol: 7, Pages: 1709-1715, ISSN: 1477-0520
Busch GK, Tate EW, Gaffney PR, et al., 2008, Specific N-terminal protein labelling: use of FMDV 3C pro protease and native chemical ligation, Chem.Commun.(Camb.), Pages: 3369-3371
We report an effective strategy for generating N-terminal cysteinyl proteins by proteolytic cleavage using the enzyme 3C pro, suitable for a wide range of applications via native chemical ligation
Panchal N, Fernandez-Yarza A, Free P, et al., 2008, Efficient preparation of 4-methoxy-5,6-dihydro-2H-pyran, Tetrahedron Letters, Vol: 49, Pages: 1836-1838, ISSN: 0040-4039
We report the efficient synthesis of 4-methoxy-5,6-dihydro-2H-pyran (MDHP) via the TiCl4 driven elimination of MeOH from 4,4-dimethoxytetrahydropyran. The previous difficulty of preparing MDHP restricted the wider use of 4-methoxytetrahydropyran-4-yl (MTHP) acyclic acetals, which have desirable protecting group properties when compared to more commonly used MOM- and THP-acetals. The behaviour of the elimination on related acetals is also examined. © 2008 Elsevier Ltd. All rights reserved.
Charles RL, Schroder E, May G, et al., 2007, Protein sulfenation as a redox sensor: Proteomic studies using a novel biotinylatied dimedone analogue, Molecular and Ceullular Proteomics, Vol: 6, Pages: 1473-1484
Chan H-L, Gaffney PR, Waterfield MD, et al., 2006, Proteomic analysis of UVC irradiation-induced damage of plasma proteins: Serum amyloid P component as a major target of photolysis, FEBS LETTERS, Vol: 580, Pages: 3229-3236, ISSN: 0014-5793
Gaffney PRJ, 2006, Chemical Genetics, Editors: Larijana B, Woscholski R, Rosser J, Publisher: Wiley & Sons
Chan HL, Gharbi S, Gaffney PR, et al., 2005, Proteomic analysis of redox- and ErbB2-dependent changes in mammary luminal epithelial cells using cysteine- and lysine-labelling two-dimensional difference gel electrophoresis, PROTEOMICS, Vol: 5, Pages: 2908-2926, ISSN: 1615-9853
Gaffney PRJ, 2005, That chemist pose is a classic because we do it , Nature, Vol: 434, ISSN: 0028-0836
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