Kimberly Watson | University of Reading (original) (raw)

Papers by Kimberly Watson

Journal of Structural Biology, Sep 1, 2021

Journal of the Chemical Society, 1993

International Journal of Molecular Sciences, Jan 29, 2020

Canadian Journal of Chemistry, Jul 1, 1990

The title complex crystallizes in the space group Pcab with a = 16.019(7), b = 19.62(1), c = 15.8... more The title complex crystallizes in the space group Pcab with a = 16.019(7), b = 19.62(1), c = 15.847(5) Å, and Z = 8. The structure was solved by direct methods and refined by full matrix least-quares calculations to a residual, R, of 0.083. The monomeric structure lacks a true centre of symmetry although the two lithiums have similar chemical environments. Each lithium cation is coordinated to three different oxygens of the hexaether and to both phenoxide oxygens. The hexaether is slightly elongated allowing both Li(1) and Li(2) to lie in the cavity formed by the crown with values of −0.077 and 0.074 Å, respectively, out of the plane approximated by the six oxygens. Both cations are strongly associated with the phenol moieties. The distances between the lithium and the phenoxide oxygens range from 1.859–1.893 Å, while distances of 1.940–2.420 Å are found with the ether oxygens. The Li(1)—Li(2) distance is found to be relatively short at 2.35 (2) Å.Evidence for motion in the 18-crown-6 portion of the solid complex has been obtained from 13C CPMAS NMR spectroscopy. At 298 K, a dipolar washout phenomenon occurs since the motional correlation times are of the order of the inverse of the 1H decoupling field amplitude. At lower temperatures, the motion becomes slow enough to permit resolution of the chemical shift differences of unique carbon sites of the crown ether. Consistent with the X-ray analysis, only five resonances are evident for the phenoxide carbons, indicating that the two aromatic rings are nearly equivalent in their crystallographic environment. The solution 13C spectrum shows only five resonances in total down to 188 K indicative of rapid conformational averaging of all the 18-crown-6 carbon resonances and rapid rotation about the O-phenyl bond. Keywords: crown ethers, NMR, stereochemistry, dynamics, X-ray.

Acta Crystallographica Section A, Aug 8, 1996

International Journal of Molecular Sciences, Oct 28, 2021

$Research paper thumbnail of Overproduction, purification and preliminary X-ray diffraction analysis of YncE, an iron-regulated Sec-dependent periplasmic protein fromEscherichia coli$

Acta crystallographica, Sep 30, 2008

$Research paper thumbnail of Preliminary X-ray diffraction analysis of YqjH fromEscherichia coli: a putative cytoplasmic ferri-siderophore reductase$

Acta crystallographica, Aug 9, 2008

Synlett, 1997

A short synthesis of the spirohydantoin of glucopyranose 1β [a potent and specific inhibitor of g... more A short synthesis of the spirohydantoin of glucopyranose 1β [a potent and specific inhibitor of glycogen phosphorylase], together with its inactive anomer 1α, from a readily available heptonolactone is described; this is the first synthesis of a spirohydantoin of a pyranose in ...

ChemMedChem, 2007

As a continuing effort to establish the structure-activity relationships (SARs) within the series... more As a continuing effort to establish the structure-activity relationships (SARs) within the series of the angiotensin II antagonists (sartans), a pharmacophoric model was built by using novel TOPP 3D descriptors. Statistical values were satisfactory (PC4: r(2)=0.96, q(2) ((5) (random) (groups))=0.84; SDEP=0.26) and encouraged the synthesis and consequent biological evaluation of a series of new pyrrolidine derivatives. SAR together with a combined 3D quantitative SAR and high-throughput virtual screening showed that the newly synthesized 1-acyl-N-(biphenyl-4-ylmethyl)pyrrolidine-2-carboxamides may represent an interesting starting point for the design of new antihypertensive agents. In particular, biological tests performed on CHO-hAT(1) cells stably expressing the human AT(1) receptor showed that the length of the acyl chain is crucial for the receptor interaction and that the valeric chain is the optimal one.

PLOS ONE, Aug 12, 2013

Methods for recombinant production of eukaryotic membrane proteins, yielding sufficient quantity ... more Methods for recombinant production of eukaryotic membrane proteins, yielding sufficient quantity and quality of protein for structural biology, remain a challenge. We describe here, expression and purification optimisation of the human SERCA2a cardiac isoform of Ca 2+ translocating ATPase, using Saccharomyces cerevisiae as the heterologous expression system of choice. Two different expression vectors were utilised, allowing expression of Cterminal fusion proteins with a biotinylation domain or a GFP-His 8 tag. Solubilised membrane fractions containing the protein of interest were purified onto Streptavidin-Sepharose, Ni-NTA or Talon resin, depending on the fusion tag present. Biotinylated protein was detected using specific antibody directed against SERCA2 and, advantageously, GFP-His 8 fusion protein was easily traced during the purification steps using in-gel fluorescence. Importantly, talon resin affinity purification proved more specific than Ni-NTA resin for the GFP-His 8 tagged protein, providing better separation of oligomers present, during size exclusion chromatography. The optimised method for expression and purification of human cardiac SERCA2a reported herein, yields purified protein (> 90%) that displays a calciumdependent thapsigargin-sensitive activity and is suitable for further biophysical, structural and physiological studies. This work provides support for the use of Saccharomyces cerevisiae as a suitable expression system for recombinant production of multi-domain eukaryotic membrane proteins.

Acta Crystallographica, Aug 5, 2014

Galactooligosaccharides (GOS) constitute an important class of prebiotic compounds used by the fo... more Galactooligosaccharides (GOS) constitute an important class of prebiotic compounds used by the food industry as active ingredients with potential health benefits. GOS are enzymatically produced from lactose using β-galactosidases through a reaction known as transgalactosylation. Many studies have been conducted in an attempt to increase GOS yields by controlling the reaction conditions using β-galactosidases from a range of microorganisms. In this study, we have used high-throughput protein engineering for two GOS producing β-galactosidases, BbgIII and BbgIV from Bifidobacterium bifidum in an effort to enhance transgalactosylation activity (over hydrolysis) thus favouring GOS synthesis. A total of 36 and 11 C-and N-terminus deletion mutants were designed for BbgIII and BbgIV, respectively. The mutant constructs ranged from highly active to completely inactive enzymes. Selected constructs were tested for their transgalactosylation activity. An increase ranging between 5 and 10% (of total carbohydrates) was obtained with the mutant enzymes. Additionally, up to 2-fold increase in the higher degree of polymerization of GOS products was observed for selected mutants compared to the native enzyme. Structure determination of two highly active constructs at 2.0 Å resolution indicated that truncations affected the oligomeric state of the enzymes, which may have implications for activity.

Biometals, Mar 29, 2022

proteins. Metal binding studies, using SRCD and ICP-OES, reveal a preference of EfeM Psy for copp... more proteins. Metal binding studies, using SRCD and ICP-OES, reveal a preference of EfeM Psy for copper, iron and zinc. This work provides detailed knowledge of the structural scaffold, the metal site geometry, and the divalent metal binding potential of EfeM. This work provides crucial underpinning for a more detailed understanding of the role of EfeM/EfeO proteins and the peptidase-M75 domains in EfeUOB/M iron uptake systems in bacteria. Keywords X-ray crystallography • EfeM • Peptidase-M75 domain • Acidic patch • Metalbinding • EfeUOB iron-transport system Abstract EfeUOB/M has been characterised in Pseudomonas syringae pathovar. syringae as a novel type of ferrous-iron transporter, consisting of an inner-membrane protein (EfeU Psy) and three periplasmic proteins (EfeO Psy , EfeM Psy and EfeB Psy). The role of an iron permease and peroxidase function has been identified for the EfeU and EfeB proteins, respectively, but the role of EfeO/M remains unclear. EfeM Psy is an 'M75-only' EfeO-like protein with a C-terminal peptidase-M75 domain (EfeO II /EfeM family). Herein, we report the 1.6 Å resolution crystal structure of EfeM Psy , the first structural report for an EfeM component of P. syringae pv. syringae. The structure possesses the bi-lobate architecture found in other bacterial periplasmic substrate/solute binding

Carbohydrate Research, Oct 1, 1989

The crystal structure of 6-thio-P-D-fructopyranose has been determined by X-ray diffraction techn... more The crystal structure of 6-thio-P-D-fructopyranose has been determined by X-ray diffraction techniques. The compound crystallizes in the orthorhombic system, space group P&2,2,, with cell dimensions a = 9.727(5), b = 5.228(6), c = 5.363(l) A, and 2 = 4. The structure was solved by direct methods and refined by full-matrix, least-squares calculations to a residual R value of 0.029. The thiopyranoid ring is in a 2C,(~) chair conformation with the hydroxymethyl group oriented-SC (gauche) to the ring sulfur atom.

Molecules

Antiangiogenic agents attenuate tumours’ growth and metastases and are therefore beneficial as an... more Antiangiogenic agents attenuate tumours’ growth and metastases and are therefore beneficial as an adjuvant or standalone cancer regimen. Drugs with dual antiproliferative and antiangiogenic activities can achieve anticancer efficacy and overcome acquired resistance. In this study, synthetic flavones (5a,b) with reported anticancer activity, and derivatives (4b and 6a), exhibited significant inhibition of endothelial cell tube formation (40–55%, 12 h) at 1 µM, which is comparable to sunitinib (50% inhibition at 1 µM, 48 h). Flavones (4b, 5a,b and 6a) also showed 25–37% reduction in HUVECs migration at 10 µM. In a Western blotting assay, 5a and 5b subdued VEGFR2 phosphorylation by 37% and 57%, respectively, suggesting that VEGFR2 may be their main antiangiogenic target. 5b displayed the best docking fit with VEGFR2 in an in silico study, followed by 5a, emphasizing the importance of the 7-hydroxyl group accompanied by a 4−C=S for activity. Conversely, derivatives with a 4-carbonyl moi...

European Journal of Pharmacology, 2019

Isorhapontigenin is a polyphenolic compound found in Chinese herbs and grapes. It is a methoxylat... more Isorhapontigenin is a polyphenolic compound found in Chinese herbs and grapes. It is a methoxylated analogue of a stilbenoid, resveratrol, which is well-known for its various beneficial effects including anti-platelet activity. Isorhapontigenin possesses greater oral bioavailability than resveratrol and has also been identified to possess anti-cancer and anti-inflammatory properties. However, its effects on platelet function have not been reported previously. In this study, we report the effects of isorhapontigenin on the modulation of platelet function. Isorhapontigenin was found to selectively inhibit ADP-induced platelet aggregation with an IC50 of 1.85µM although it displayed marginal inhibition on platelet aggregation induced by other platelet agonists at 100µM. However, resveratrol exhibited weaker inhibition on ADP-induced platelet aggregation (IC50>100µM) but inhibited collagen induced platelet aggregation at 50µM and 100µM. Isorhapontigenin also inhibited integrin αIIbβ3 mediated inside-out and outside-in signalling and dense granule secretion in ADP-induced platelet activation but interestingly, no effect was observed on α-granule secretion. Isorhapontigenin did not exert any cytotoxicity on platelets at the concentrations of up to 100µM. Furthermore, it did not affect haemostasis in mice at the IC50 concentration (1.85µM). In addition, the mechanistic studies demonstrated that isorhapontigenin increased cAMP levels and VASP phosphorylation at Ser157 and decreased Akt phosphorylation. This suggests that isorhapontigenin may interfere with cAMP and PI3K signalling pathways that are associated with the P2Y12 receptor. Molecular docking studies emphasised that isorhapontigenin has greater binding affinity to P2Y12 receptor than resveratrol. Our results demonstrate that isorhapontigenin has selective inhibitory effects on ADP-stimulated platelet activation possibly via P2Y12 receptor.