127 results on '"Harvey, Peta J."'
Search Results
102. Spectroscopic and structural studies on 1 : 2 adducts of silver(I) salts with tricyclohexylphosphine.
- Author
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Bowmaker, Graham A., Effendy, Harvey, Peta J., Healy, Peter C., Skelton, Brian W., and White, Allan H.
- Published
- 1996
- Full Text
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103. Spectroscopic and structural studies on 1 : 1 adducts of silver(I) salts with tricyclohexylphosphine.
- Author
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Bowmaker, Graham A., Effendy, Harvey, Peta J., Healy, Peter C., Skelton, Brian W., and White, Allan H.
- Published
- 1996
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104. 31P and 1H NMR spectroscopic studies of liver extracts of carbon tetrachloride‐treated rats
- Author
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Harvey, Peta J., Gready, Jill E., Hickey, Haruyo M., Le Couteur, David G., and McLean, Allan J.
- Abstract
NMR spectroscopy was used to examine hepatic metabolism in cirrhosis with a particular focus on markers of functional cellular hypoxia. 31P and 1H NMR spectra were obtained from liver extracts from control rats and from rats with carbon tetrachloride‐induced cirrhosis. A decrease of 34% in total phosphorus content was observed in cirrhotic rats, parallelling a reduction of 40% in hepatocyte mass as determined by morphometric analysis. Hypoxia appeared to be present in cirrhotic rats, as evidenced by increased inorganic phosphate levels, decreased ATP levels, decreased ATP:ADP ratios (1.72 ± 0.40 vs 2.48 ± 0.50, p< 0.01), and increased inorganic phosphate:ATP ratios (2.77 ± 0.48 vs 1.62 ± 0.24, p< 0.00001). When expressed as a percentage of the total phosphorus content, higher levels of phosphoethanolamine and lower levels of NAD and glycerophosphoethanolamine were detected in cirrhotic rats. Cirrhotic rats also had increased phosphomonoester:phosphodiester ratios (5.73 ± 2.88 vs 2.53 ± 0.52, p< 0.01). These findings are indicative of extensive changes in cellular metabolism in the cirrhotic liver, with many findings attributable to the presence of intracellular hypoxia. Copyright © 1999 John Wiley & Sons, Ltd.
- Published
- 1999
- Full Text
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105. <SUP>31</SUP>P and <SUP>1</SUP>H NMR spectroscopic studies of liver extracts of carbon tetrachloride-treated rats
- Author
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Harvey, Peta J., Gready, Jill E., Hickey, Haruyo M., and Couteur, David G. Le
- Abstract
NMR spectroscopy was used to examine hepatic metabolism in cirrhosis with a particular focus on markers of functional cellular hypoxia. 31P and 1H NMR spectra were obtained from liver extracts from control rats and from rats with carbon tetrachloride-induced cirrhosis. A decrease of 34% in total phosphorus content was observed in cirrhotic rats, parallelling a reduction of 40% in hepatocyte mass as determined by morphometric analysis. Hypoxia appeared to be present in cirrhotic rats, as evidenced by increased inorganic phosphate levels, decreased ATP levels, decreased ATP:ADP ratios (1.72 ± 0.40 vs 2.48 ± 0.50, p < 0.01), and increased inorganic phosphate:ATP ratios (2.77 ± 0.48 vs 1.62 ± 0.24, p < 0.00001). When expressed as a percentage of the total phosphorus content, higher levels of phosphoethanolamine and lower levels of NAD and glycerophosphoethanolamine were detected in cirrhotic rats. Cirrhotic rats also had increased phosphomonoester:phosphodiester ratios (5.73 ± 2.88 vs 2.53 ± 0.52, p < 0.01). These findings are indicative of extensive changes in cellular metabolism in the cirrhotic liver, with many findings attributable to the presence of intracellular hypoxia. Copyright © 1999 John Wiley & Sons, Ltd.
- Published
- 1999
- Full Text
- View/download PDF
106. Influence of anion on the solution and solid-state structures of some 1∶2 adducts of silver(I) salts with 1,3-bis(diphenylphosphino)propane
- Author
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Affandi, Dermawan, J. Berners-Price, Susan, Berners-Price, Susan J., Effendy, Harvey, Peta J., Healy, Peter C., Ruch, Beate E., White, Allan H., J. Harvey, Peta, C. Healy, Peter, E. Ruch, Beate, and H. White, Allan
- Abstract
Crystallization of 1∶2 silver(I) halide/pseudo halide∶1,3-bis(diphenylphosphino)propane (dppp) mixtures from acetonitrile have resulted in the isolation of a novel series of neutral complexes, [AgX(dppp-P,P′)(dppp-P)] (X = Cl, Br, I or CN) containing co-ordinated anion and uni- and bi-dentate dppp ligands. In contrast, the thiocyanate and nitrate complexes precipitate as ionic [Ag(dppp-P,P′)2]X with unco-ordinated anion and bidentate phosphine ligands, a structural type previously found for other 1∶2 silver(I)∶diphosphine complexes. The complexes have been characterized by single-crystal X-ray structure determinations and solid-state 31P cross-polarization magic angle spinning (CP MAS) NMR spectroscopy. The salt [Ag(dppp-P,P′)2]SCN is obtained as crystals suitable for X-ray studies from pyridine, crystallizing as a sesqui-pyridine solvate in the monoclinic space group P21/c with a = 10.691(2), b = 24.75(2), c = 22.360(4) Å, β = 108.38(1)°. The neutral AgXP3 complexes (X = Cl, Br, I or CN) are isomorphous, crystallizing in the monoclinic space group C2/c, with a ≈ 21.8, b ≈ 10.3, c ≈ 45 Å, β ≈ 95°. The solid-state 31P CP MAS spectra are consistent with the structural results; the tetrahedral SCN and NO3 complexes give a similar broad complex multiplet centred at δ -6, whereas the spectra of the neutral AgXP3 complexes are interpretable as A2BMX spin systems with signals assignable to the non-co-ordinated (δ -23), bidentate (δ ca. 13) and unidentate (δ ca. 3) phosphorus atoms. For the latter 1J(P–Ag) couplings are in the range 288 Hz (CN) to 367 Hz (Br). Solution 31P NMR studies on these complexes show that both neutral and ionic complexes exist in equilibrium in solution, with the position of the equilibrium dependent on the nature of the anion X. The potential significance to the antitumour activity of bis-chelated 1∶2 silver(I)–diphosphine complexes is discussed.
- Published
- 1997
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107. Silver(I) nitrate adducts with bidentate 2-, 3- and 4-pyridyl phosphines. Solution <SUP>31</SUP>P and [<SUP>31</SUP>P&z.sbd6;<SUP>109</SUP>Ag] NMR studies of 1∶2 complexes and crystal structure of dimeric [{Ag(d2pype)(μ-d2pype)}<SUB>2</SUB>][NO<SUB>3</SUB>]<SUB>2</SUB>·2CH<SUB>2</SUB>Cl<SUB>2</SUB> [d2pype = 1,2-bis(di-2-pyridylphosphino)ethane]
- Author
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Berners-Price, Susan J., Bowen, Richard J., Harvey, Peta J., Healy, Peter C., and Koutsantonis, George A.
- Abstract
The 1∶2 complexes of silver(I) nitrate with 1,2-bis(di-n-pyridylphosphino)ethane (dnpype) for n = 2, 3 and 4 have been synthesized and solution properties characterized by NMR spectroscopy, including variable-temperature one-dimensional 31P-{1H}, two-dimensional [31P&z.sbd6;31P] COSY and [31P&z.sbd6;109Ag] HMQC NMR experiments. The 3-pyridyl (d3pype) and 4-pyridyl (d4pype) complexes exist as bis-chelated monomeric [Ag(d3pype)2]+ and [Ag(d4pype)2]+ while the 2-pyridyl (d2pype) complex forms an equilibrium mixture of monomeric [Ag(d2pype)2]+, dimeric [{Ag(d2pype)2}2]2+ and trimeric [{Ag(d2pype)2}3]3+ species in which the d2pype ligands co-ordinate in both bridging and chelated modes via the phosphorus atoms. The relative percentages of the species present are dependent on both temperature and solvent. Crystals of the 2-pyridyl complex obtained from CH2Cl2Et2O solution have been shown by crystal structure determination to be the dimer [{Ag(d2pype)(μ-d2pype)}2][NO3]2·2CH2Cl2. Each silver ion is co-ordinated by one chelated and two bridging d2pype ligands forming a ten-membered ring in a double boat conformation. The pyridyl nitrogen atoms do not co-ordinate to the silver. The differences in solution behaviour of the three systems and the potential significance of these complexes to the antitumour properties of chelated 1∶2 silver(I) diphosphine complexes are discussed.
- Published
- 1998
108. Oxidative Injury Reproduces Age-Related Impairment of Oxygen-Dependent Drug Metabolism.
- Author
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Couteur, David G., Hickey, Haruyo M., Harvey, Peta J., and McLean, Allan J.
- Abstract
The Oxygen Diffusion Barrier Hypothesis states that aging in the liver is associated with restricted oxygen uptake that explains the age-related impairment of phase I drug clearance observed in vivo with preservation of in vitro phase I enzyme activity and in vivo phase II drug clearance. Aging in the liver may be secondary to oxidative stress. Therefore we examined the effects of oxidative injury on oxygen uptake, and phase I and phase II drug metabolism in the liver. Oxidative stress was induced in the perfused rat liver with hydrogen peroxide. The intrinsic clearances of propranolol and morphine were used as markers of phase I and phase II activity, respectively. Oxidative injury was associated with a 14$pL9% (P=0.03) reduction in oxygen uptake. The decrease in the intrinsic clearance of propranolol was greater than that of morphine (57$pL14% vs 34$pL7% P<0.005). This result supports the concept of a restriction of oxygen supply constraining hepatic drug metabolism following oxidative stress. This has implications for aging and hepatic drug metabolism. [ABSTRACT FROM AUTHOR]
- Published
- 1999
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109. NMR Structure of μ-Conotoxin GIIIC: Leucine 18 Induces Local Repacking of the N-Terminus Resulting in Reduced NaV Channel Potency.
- Author
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Harvey, Peta J., Kurniawan, Nyoman D., Finol-Urdaneta, Rocio K., McArthur, Jeffrey R., Van Lysebetten, Dorien, Dash, Thomas S., Hill, Justine M., Adams, David J., Durek, Thomas, and Craik, David J.
- Subjects
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CONOTOXINS , *SODIUM channels , *LEUCINE , *AMINO acids , *SUBSTITUENTS (Chemistry) , *PEPTIDES - Abstract
μ-Conotoxins are potent and highly specific peptide blockers of voltage-gated sodium channels. In this study, the solution structure of μ-conotoxin GIIIC was determined using 2D NMR spectroscopy and simulated annealing calculations. Despite high sequence similarity, GIIIC adopts a three-dimensional structure that differs from the previously observed conformation of μ-conotoxins GIIIA and GIIIB due to the presence of a bulky, non-polar leucine residue at position 18. The side chain of L18 is oriented towards the core of the molecule and consequently the N-terminus is re-modeled and located closer to L18. The functional characterization of GIIIC defines it as a canonical μ-conotoxin that displays substantial selectivity towards skeletal muscle sodium channels (NaV), albeit with ~2.5-fold lower potency than GIIIA. GIIIC exhibited a lower potency of inhibition of NaV1.4 channels, but the same NaV selectivity profile when compared to GIIIA. These observations suggest that single amino acid differences that significantly affect the structure of the peptide do in fact alter its functional properties. Our work highlights the importance of structural factors, beyond the disulfide pattern and electrostatic interactions, in the understanding of the functional properties of bioactive peptides. The latter thus needs to be considered when designing analogues for further applications. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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110. Short Communication Hepatic Phospholipid Changes Induced by Sustained Oxygen Supplementation
- Author
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Harvey, Peta J., Gready, Jill E., Yin, Zhanli, Le Couteur, David G., and McLean, Allan J.
- Published
- 2002
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111. Letter to the Editor: 1H, 13C and 15N assignments for the II–III loop region of the skeletal dyhydropyridine receptor.
- Author
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Yanfang Cui, Karunasekara, Yamuna, Harvey, Peta J., Board, Philip G., Dulhunty, Angela F., and Casarotto, Marco G.
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LETTERS to the editor ,NUCLEAR magnetic resonance - Abstract
Presents a letter to the editor published in the periodical "Journal of Biomolecular NMR," discussing the characteristics of the skeletal dyhydropyridine receptor.
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- 2005
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112. Erratum: The self-association of the cyclotide kalata B2 in solution is guided by hydrophobic interactions.
- Author
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Johan Rosengren, K., Daly, Norelle L., Harvey, Peta J., and Craik, David J.
- Published
- 2014
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113. Design, synthesis, and mechanism of action of novel μ-conotoxin KIIIA analogues for inhibition of the voltage-gated sodium channel Nav1.7.
- Author
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Zitong Zhao, Teng Pan, Shen Chen, Harvey, Peta J., Jinghui Zhang, Xiao Li, Mengke Yang, Linhong Huang, Shoushi Wang, Craik, David J., Tao Jiang, and Rilei Yu
- Subjects
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SODIUM channels , *MOLECULAR dynamics , *PEPTIDES , *SODIUM channel blockers , *PAIN management - Abstract
µ-Conotoxin KIIIA, a selective blocker of sodium channels, has strong inhibitory activity against several Nav isoforms, including Nav1.7, and has potent analgesic effects, but it contains three pairs of disulfide bonds, making structural modification difficult and synthesis complex. To circumvent these difficulties, we designed and synthesized three KIIIA analogues with one disulfide bond deleted. The most active analogue, KIIIA-1, was further analyzed, and its binding pattern to hNav1.7 was determined by molecular dynamics simulations. Guided by the molecular dynamics computational model, we designed and tested 32 second-generation and 6 thirdgeneration analogues of KIIIA-1 on hNav1.7 expressed in HEK293 cells. Several analogues showed significantly improved inhibitory activity on hNav1.7, and the most potent peptide, 37, was approximately 4-fold more potent than the KIIIA Isomer I and 8-fold more potent than the wildtype (WT) KIIIA in inhibiting hNav1.7 current. Intraperitoneally injected 37 exhibited potent in vivo analgesic activity in a formalininduced inflammatory pain model, with activity reaching -350-fold of the positive control drug morphine. Overall, peptide 37 has a simplified disulfide-bond framework and exhibits potent in vivo analgesic effects and has promising potential for development as a pain therapy in the future. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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114. The acyclotide ribe 31 from Rinorea bengalensis has selective cytotoxicity and potent insecticidal properties in Drosophila.
- Author
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Tien T. Dang, Yen-Hua Huang, Ott, Stanislav, Harvey, Peta J., Gilding, Edward K., Tombling, Benjamin J., Lai Y. Chan, Kaas, Quentin, Claridge-Chang, Adam, and Craik, David J.
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DROSOPHILIDAE , *SURFACE plasmon resonance , *DROSOPHILA , *DROSOPHILA melanogaster , *ERYTHROCYTES - Abstract
Cyclotides and acyclic versions of cyclotides (acyclotides) are peptides involved in plant defense. These peptides contain a cystine knot motif formed by three interlocked disulfide bonds, with the main difference between the two classes being the presence or absence of a cyclic backbone, respectively. The insecticidal activity of cyclotides is well documented, but no study to date explores the insecticidal activity of acyclotides. Here, we present the first in vivo evaluation of the insecticidal activity of acyclotides from Rinorea bengalensis on the vinegar fly Drosophila melanogaster. Of a group of structurally comparable acyclotides, ribe 31 showed the most potent toxicity when fed to D. melanogaster. We screened a range of acyclotides and cyclotides and found their toxicity toward human red blood cells was substantially lower than toward insect cells, highlighting their selectivity and potential for use as bioinsecticides. Our confocal microscopy experiments indicated their cytotoxicity is likely mediated via membrane disruption. Furthermore, our surface plasmon resonance studies suggested ribe 31 preferentially binds to membranes containing phospholipids with phosphatidyl-ethanolamine headgroups. Despite having an acyclic backbone, we determined the three-dimensional NMR solution structure of ribe 31 is similar to that of cyclotides. In summary, our results suggest that, with further optimization, ribe 31 could have applications as an insecticide due to its potent in vivo activity against D. melanogaster. More broadly, this work advances the field by demonstrating that acyclotides are more common than previously thought, have potent insecticidal activity, and have the advantage of potentially being more easily manufactured than cyclotides. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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115. Neurotoxic and cytotoxic peptides underlie the painful stings of the tree nettle Urtica ferox.
- Author
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Jing Xie, Robinson, Samuel D., Gilding, Edward K., Jami, Sina, Deuis, Jennifer R., Rehm, Fabian B. H., Yap, Kuok, Ragnarsson, Lotten, Lai Yue Chan, Hamilton, Brett R., Harvey, Peta J., Craik, David J., Vetter, Irina, and Durek, Thomas
- Subjects
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STINGING nettle , *PEPTIDES , *SODIUM channels , *ACTIVATION energy , *CELL membranes , *TOXINS - Abstract
The stinging hairs of plants from the family Urticaceae inject compounds that inflict pain to deter herbivores. The sting of the New Zealand tree nettle (Urtica ferox) is among the most painful of these and can cause systemic symptoms that can even be life-threatening; however, the molecular species effecting this response have not been elucidated. Here we reveal that two classes of peptide toxin are responsible for the symptoms of U. ferox stings: Δ-Uf1a is a cytotoxic thionin that causes pain via disruption of cell membranes, while β/δ-Uf2a defines a new class of neurotoxin that causes pain and systemic symptoms via modulation of voltage-gated sodium (NaV) channels. We demonstrate using whole-cell patch-clamp electrophysiology experiments that β/δ-Uf2a is a potent modulator of human NaV1.5 (EC50: 55 nM), NaV1.6 (EC50: 0.86 nM), and NaV1.7 (EC50: 208 nM), where it shifts the activation threshold to more negative potentials and slows fast inactivation. We further found that both toxin classes are widespread among members of the Urticeae tribe within Urticaceae, suggesting that they are likely to be pain-causing agents underlying the stings of other Urtica species. Comparative analysis of nettles of Urtica, and the recently described pain-causing peptides from nettles of another genus, Dendrocnide, indicates that members of tribe Urticeae have developed a diverse arsenal of pain-causing peptides. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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116. Backbone cyclization of analgesic conotoxin GeXIVA facilitates direct folding of the ribbon isomer.
- Author
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Xiaosa Wu, Yen-Hua Huang, Kaas, Quentin, Harvey, Peta J., Wang, Conan K., Han-Shen Tae, Adams, David J., and Craik, David J.
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CONOTOXINS , *CHOLINERGIC receptors , *PEPTIDES , *CHEMICAL yield , *DISULFIDES - Abstract
Conotoxin GeXIVA inhibits the α9α10 nicotinic acetylcholine receptor (nAChR) and is analgesic in animal models of pain. α-Conotoxins have four cysteines that can have three possible disulfide connectivities: globular (CysI-CysIII and CysII-CysIV), ribbon (CysI-CysIV and CysII-CysIII), or bead (CysI-CysII and CysIII-CysIV). Native α-conotoxins preferably adopt the globular connectivity, and previous studies of α-conotoxins have focused on the globular isomers as the ribbon and bead isomers typically have lower potency at nAChRs than the globular form. A recent report showed that the bead and ribbon isomers of GeXIVA are more potent than the globular isomer, with low nanomolar half-maximal inhibitory concentrations (IC50). Despite this high potency, the therapeutic potential of GeXIVA is limited, because like most peptides, it is susceptible to proteolytic degradation and is challenging to synthesize in high yield. Here we used backbone cyclization as a strategy to improve the folding yield as well as increase the serum stability of ribbon GeXIVA while preserving activity at the α9α10 nAChR. Specifically, cyclization of ribbon GeXIVA with a two-residue linker maintained the biological activity at the human α9α10 nAChR and improved stability in human serum. Short linkers led to selective formation of the ribbon disulfide isomer without requiring orthogonal protection. Overall, this study highlights the value of backbone cyclization in directing folding, improving yields, and stabilizing conotoxins with therapeutic potential. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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117. Recombinant production of the cyclotide kalata B1 by conditional split inteins.
- Author
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Craik DJ, Yayci A, Huang YH, and Harvey PJ
- Abstract
This study describes the design, production, and characterization of a novel conditional intein system for the recombinant production of cyclic peptides. The system is based on two key features: (1) a promiscuous extein recognition site allowing cyclization of virtually any peptide, and (2) a secondary split site within the intein itself enabling triggered splicing at will. Two intein precursors were recombinantly expressed, purified, and then self-assembled in vitro to cyclize the model peptide kalata B1 (kB1). Cyclized kB1 was successfully purified, refolded and characterized by mass spectrometry and NMR, demonstrating correct disulfide bond formation and identical structure to synthetic kB1. Importantly, the intein-derived kB1 retained full biological activity as evidenced by insect cell toxicity assays. This work establishes a versatile and efficient approach for intein-mediated protein cyclization with potential applications in bioengineering and peptide discovery., (© 2024 Wiley‐VCH GmbH.)
- Published
- 2024
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118. A Chemoenzymatic Approach To Produce a Cyclic Analogue of the Analgesic Drug MVIIA (Ziconotide).
- Author
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Zhou Y, Harvey PJ, Koehbach J, Chan LY, Jones A, Andersson Å, Vetter I, Durek T, and Craik DJ
- Subjects
- Humans, Analgesics pharmacology, Analgesics therapeutic use, Calcium Channels chemistry, Calcium Channel Blockers pharmacology, omega-Conotoxins pharmacology, omega-Conotoxins therapeutic use, Conotoxins pharmacology
- Abstract
Ziconotide (ω-conotoxin MVIIA) is an approved analgesic for the treatment of chronic pain. However, the need for intrathecal administration and adverse effects have limited its widespread application. Backbone cyclization is one way to improve the pharmaceutical properties of conopeptides, but so far chemical synthesis alone has been unable to produce correctly folded and backbone cyclic analogues of MVIIA. In this study, an asparaginyl endopeptidase (AEP)-mediated cyclization was used to generate backbone cyclic analogues of MVIIA for the first time. Cyclization using six- to nine-residue linkers did not perturb the overall structure of MVIIA, and the cyclic analogues of MVIIA showed inhibition of voltage-gated calcium channels (Ca
V 2.2) and substantially improved stability in human serum and stimulated intestinal fluid. Our study reveals that AEP transpeptidases are capable of cyclizing structurally complex peptides that chemical synthesis cannot achieve and paves the way for further improving the therapeutic value of conotoxins., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)- Published
- 2023
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119. Design, synthesis, and mechanism of action of novel μ-conotoxin KIIIA analogues for inhibition of the voltage-gated sodium channel Na v 1.7.
- Author
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Zhao Z, Pan T, Chen S, Harvey PJ, Zhang J, Li X, Yang M, Huang L, Wang S, Craik DJ, Jiang T, and Yu R
- Subjects
- Humans, Disulfides metabolism, HEK293 Cells, Molecular Dynamics Simulation, Pain chemically induced, Pain drug therapy, Peptides pharmacology, Peptides metabolism, Analgesics pharmacology, Analgesics chemistry, Conotoxins chemistry, Conotoxins pharmacology, NAV1.7 Voltage-Gated Sodium Channel, Voltage-Gated Sodium Channel Blockers chemistry, Voltage-Gated Sodium Channel Blockers pharmacology
- Abstract
μ-Conotoxin KIIIA, a selective blocker of sodium channels, has strong inhibitory activity against several Na
v isoforms, including Nav 1.7, and has potent analgesic effects, but it contains three pairs of disulfide bonds, making structural modification difficult and synthesis complex. To circumvent these difficulties, we designed and synthesized three KIIIA analogues with one disulfide bond deleted. The most active analogue, KIIIA-1, was further analyzed, and its binding pattern to hNav 1.7 was determined by molecular dynamics simulations. Guided by the molecular dynamics computational model, we designed and tested 32 second-generation and 6 third-generation analogues of KIIIA-1 on hNav 1.7 expressed in HEK293 cells. Several analogues showed significantly improved inhibitory activity on hNav 1.7, and the most potent peptide, 37, was approximately 4-fold more potent than the KIIIA Isomer I and 8-fold more potent than the wildtype (WT) KIIIA in inhibiting hNav 1.7 current. Intraperitoneally injected 37 exhibited potent in vivo analgesic activity in a formalin-induced inflammatory pain model, with activity reaching ∼350-fold of the positive control drug morphine. Overall, peptide 37 has a simplified disulfide-bond framework and exhibits potent in vivo analgesic effects and has promising potential for development as a pain therapy in the future., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)- Published
- 2023
- Full Text
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120. Application and Structural Analysis of Triazole-Bridged Disulfide Mimetics in Cyclic Peptides.
- Author
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White AM, de Veer SJ, Wu G, Harvey PJ, Yap K, King GJ, Swedberg JE, Wang CK, Law RHP, Durek T, and Craik DJ
- Subjects
- Amino Acid Sequence, Crystallography, X-Ray, Cyclization, Nuclear Magnetic Resonance, Biomolecular, Ruthenium chemistry, Disulfides chemistry, Molecular Mimicry, Peptides, Cyclic chemistry, Triazoles chemistry
- Abstract
Ruthenium-catalysed azide-alkyne cycloaddition (RuAAC) provides access to 1,5-disubstituted 1,2,3-triazole motifs in peptide engineering applications. However, investigation of this motif as a disulfide mimetic in cyclic peptides has been limited, and the structural consequences remain to be studied. We report synthetic strategies to install various triazole linkages into cyclic peptides through backbone cyclisation and RuAAC cross-linking reactions. These linkages were evaluated in four serine protease inhibitors based on sunflower trypsin inhibitor-1. NMR and X-ray crystallography revealed exceptional consensus of bridging distance and backbone conformations (RMSD<0.5 Å) of the triazole linkages compared to the parent disulfide molecules. The triazole-bridged peptides also displayed superior half-lives in liver S9 stability assays compared to disulfide-bridged peptides. This work establishes a foundation for the application of 1,5-disubstituted 1,2,3-triazoles as disulfide mimetics., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2020
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121. Stabilization of the cysteine-rich conotoxin MrIA by using a 1,2,3-triazole as a disulfide bond mimetic.
- Author
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Gori A, Wang CI, Harvey PJ, Rosengren KJ, Bhola RF, Gelmi ML, Longhi R, Christie MJ, Lewis RJ, Alewood PF, and Brust A
- Subjects
- Amino Acid Sequence, Click Chemistry, Conotoxins metabolism, Drug Design, Norepinephrine Plasma Membrane Transport Proteins antagonists & inhibitors, Norepinephrine Plasma Membrane Transport Proteins metabolism, Peptidomimetics, Structure-Activity Relationship, Conotoxins chemistry, Cysteine chemistry, Disulfides chemistry, Triazoles chemistry
- Abstract
The design of disulfide bond mimetics is an important strategy for optimising cysteine-rich peptides in drug development. Mimetics of the drug lead conotoxin MrIA, in which one disulfide bond is selectively replaced of by a 1,4-disubstituted-1,2,3-triazole bridge, are described. Sequential copper-catalyzed azide-alkyne cycloaddition (CuAAC; click reaction) followed by disulfide formation resulted in the regioselective syntheses of triazole-disulfide hybrid MrIA analogues. Mimetics with a triazole replacing the Cys4-Cys13 disulfide bond retained tertiary structure and full in vitro and in vivo activity as norepinephrine reuptake inhibitors. Importantly, these mimetics are resistant to reduction in the presence of glutathione, thus resulting in improved plasma stability and increased suitability for drug development., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2015
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122. The self-association of the cyclotide kalata B2 in solution is guided by hydrophobic interactions.
- Author
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Rosengren KJ, Daly NL, Harvey PJ, and Craik DJ
- Subjects
- Humans, Hydrophobic and Hydrophilic Interactions, Molecular Sequence Data, Oldenlandia chemistry, Plant Proteins chemistry, Solutions, Amino Acid Sequence, Cyclotides chemistry
- Abstract
The cyclotides are a family of small head-to-tail cyclic plant defense proteins. In addition to their cyclic backbone, cyclotides comprise three disulfide bonds in a knotted arrangement, resulting in a highly cross-braced structure that provides exceptional chemical and proteolytic stability. A number of bioactivities have been associated with cyclotides, including insecticidal, antimicrobial, anti-viral and cytotoxic, and these activities are related to an ability to target and disrupt biological membranes. Kalata B2 and to a lesser extent kalata B1, isolated from Oldenlandia affinis, self-associate to tetramers and octamers in aqueous buffers, and this oligomerization has been suggested to be relevant for their ability to form pores in membranes. Here we demonstrate by solution NMR spectroscopy analysis that the oligomerization of kalata B2 is concentration dependent and that it involves the packing of hydrophobic residues normally exposed on the surface of kalata B2 into a multimeric hydrophobic core. Interestingly, the hydrophobic surface that is "quenched" has previously been shown to be responsible for the ability of kalata B2 to insert into membranes. Thus, it seems unlikely that the oligomers observed in aqueous solution are related to any multimeric state present in a membrane environment, and responsible for the formation of pores. The ability to self-associate might alternatively provide a mechanism for preventing self-toxicity when stored at high concentrations in intracellular compartments., (Copyright © 2013 Wiley Periodicals, Inc.)
- Published
- 2013
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123. Engineering of conotoxins for the treatment of pain.
- Author
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Carstens BB, Clark RJ, Daly NL, Harvey PJ, Kaas Q, and Craik DJ
- Subjects
- Amino Acid Sequence, Analgesics chemistry, Analgesics isolation & purification, Analgesics therapeutic use, Animals, Conotoxins genetics, Conotoxins isolation & purification, Conotoxins therapeutic use, Conus Snail chemistry, Cyclization, Drug Stability, Humans, Molecular Sequence Data, Mollusk Venoms chemistry, Peptides, Cyclic genetics, Peptides, Cyclic isolation & purification, Peptides, Cyclic therapeutic use, Protein Conformation, Solid-Phase Synthesis Techniques, Analgesics chemical synthesis, Conotoxins chemical synthesis, Drug Design, Pain drug therapy, Peptides, Cyclic chemical synthesis
- Abstract
The peptides present in the venoms of marine snails are used by the snails to capture prey, but they have also attracted the interest of drug designers because of their potent activity against therapeutically important targets. These peptides are typically disulfiderich and target a wide range of ion channels, transporters and receptors with exquisite selectivity. In this article, we discuss structural and biological studies on several classes of conotoxins that have potential as drug leads for the treatment of pain. The chemical re-engineering of conotoxins via cyclization has been particularly valuable in improving their biopharmaceutical properties. An excellent example is the α-conotoxin Vc1.1, for which several cyclized analogs have been made. One of them was shown to be orally active in a rat pain model and this analog is currently undergoing pre-clinical development for the treatment of neuropathic pain. Several other α-conotoxins, including ImI, AuIB and MII, have proved amenable to cyclization and in all cases improvements in stability are obtained upon cyclization, suggesting that cyclization is a generally applicable approach to conotoxin stabilization. A variety of other chemical re-engineering approaches have also been used. Minor re-engineering of χ-conotoxin MrIa to convert its N-terminal residue to pyroglutamic acid proved particularly successful and the modified derivative, Xen2174, is currently in clinical trials for neuropathic pain.
- Published
- 2011
- Full Text
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124. Malignant hyperthermia mutation sites in the Leu2442-Pro2477 (DP4) region of RyR1 (ryanodine receptor 1) are clustered in a structurally and functionally definable area.
- Author
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Bannister ML, Hamada T, Murayama T, Harvey PJ, Casarotto MG, Dulhunty AF, and Ikemoto N
- Subjects
- Animals, Calcium metabolism, Hindlimb, Humans, Kinetics, Leucine, Malignant Hyperthermia metabolism, Models, Genetic, Models, Molecular, Proline, Protein Structure, Secondary, Rabbits, Ryanodine Receptor Calcium Release Channel chemistry, Ryanodine Receptor Calcium Release Channel metabolism, Malignant Hyperthermia genetics, Mutation, Ryanodine Receptor Calcium Release Channel genetics
- Abstract
To explain the mechanism of pathogenesis of channel disorder in MH (malignant hyperthermia), we have proposed a model in which tight interactions between the N-terminal and central domains of RyR1 (ryanodine receptor 1) stabilize the closed state of the channel, but mutation in these domains weakens the interdomain interaction and destabilizes the channel. DP4 (domain peptide 4), a peptide corresponding to residues Leu2442-Pro2477 of the central domain, also weakens the domain interaction and produces MH-like channel destabilization, whereas an MH mutation (R2458C) in DP4 abolishes these effects. Thus DP4 and its mutants serve as excellent tools for structure-function studies. Other MH mutations have been reported in the literature involving three other amino acid residues in the DP4 region (Arg2452, Ile2453 and Arg2454). In the present paper we investigated the activity of several mutants of DP4 at these three residues. The ability to activate ryanodine binding or to effect Ca2+ release was severely diminished for each of the MH mutants. Other substitutions were less effective. Structural studies, using NMR analysis, revealed that the peptide has two a-helical regions. It is apparent that the MH mutations are clustered at the C-terminal end of the first helix. The data in the present paper indicates that mutation of residues in this region disrupts the interdomain interactions that stabilize the closed state of the channel.
- Published
- 2007
- Full Text
- View/download PDF
125. Effects of an alpha-helical ryanodine receptor C-terminal tail peptide on ryanodine receptor activity: modulation by Homer.
- Author
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Pouliquin P, Pace SM, Curtis SM, Harvey PJ, Gallant EM, Zorzato F, Casarotto MG, and Dulhunty AF
- Subjects
- Animals, Homer Scaffolding Proteins, Muscle, Skeletal metabolism, Peptides antagonists & inhibitors, Peptides chemistry, Peptides pharmacology, Protein Structure, Secondary, Rabbits, Ryanodine Receptor Calcium Release Channel drug effects, Ryanodine Receptor Calcium Release Channel genetics, Carrier Proteins pharmacology, Ryanodine Receptor Calcium Release Channel chemistry
- Abstract
We have determined the structure of a domain peptide corresponding to the extreme 19 C-terminal residues of the ryanodine receptor Ca2+ release channel. We examined functional interactions between the peptide and the channel, in the absence and in the presence of the regulatory protein Homer. The peptide was partly alpha-helical and structurally homologous to the C-terminal end of the T1 domain of voltage-gated K+ channels. The peptide (0.1-10 microM) inhibited skeletal ryanodine receptor channels when the cytoplasmic Ca2+ concentration was 1 microM; but with 10 microM cytoplasmic Ca2+, skeletal ryanodine receptors were activated by < or = 1.0 microM peptide and inhibited by 10 microM peptide. Cardiac ryanodine receptors on the other hand were inhibited by all peptide concentrations, at both Ca2+ concentrations. When channels did open in the presence of the peptide, they were more likely to open to substate levels. The inhibition and increased fraction of openings to subconductance levels suggested that the domain peptide might destabilise inter-domain interactions that involve the C-terminal tail. We found that Homer 1b not only interacts with the channels, but reduces the inhibitory action of the C-terminal tail peptide, perhaps by stabilizing inter-domain interactions and preventing their disruption.
- Published
- 2006
- Full Text
- View/download PDF
126. 1H, 13C and 15N assignments for the II-III loop region of the skeletal dyhydropyridine receptor.
- Author
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Cui Y, Karunasekara Y, Harvey PJ, Board PG, Dulhunty AF, and Casarotto MG
- Subjects
- Molecular Sequence Data, Nuclear Magnetic Resonance, Biomolecular, Calcium Channels, L-Type chemistry, Carbon Isotopes chemistry, Deuterium chemistry, Muscle, Skeletal chemistry, Nitrogen Isotopes chemistry, Protein Structure, Secondary
- Published
- 2005
- Full Text
- View/download PDF
127. Role of some unconserved residues in the "C" region of the skeletal DHPR II-III loop.
- Author
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Dulhunty AF, Karunasekara Y, Curtis SM, Harvey PJ, Board PG, and Casarotto MG
- Subjects
- Calcium Channels metabolism, Calcium Channels, L-Type chemistry, Cells, Cultured, Humans, Muscle, Skeletal cytology, Peptide Fragments pharmacology, Recombinant Proteins chemistry, Recombinant Proteins metabolism, Ryanodine Receptor Calcium Release Channel chemistry, Calcium Channels, L-Type metabolism, Muscle, Skeletal metabolism, Ryanodine Receptor Calcium Release Channel metabolism
- Abstract
The actions of the recombinant skeletal dihydropyridine receptor II-III loop (SDCL), and the C region peptide (CS) on native skeletal muscle ryanodine receptor Ca2+ release channel (RyR1) have been examined. Three non conserved residues in the "C" region of the skeletal DHPR II-III loop were replaced by the equivalent cardiac residues in SDCLAFP-PTT (A739P, F741T and P742T) and single substitutions made in SDCLA-P, SDCLF-T and SDCLP-T. Wild type SDCL as well as SDCLF-T and SDCLP-T activated RyR1 in lipid bilayers with high affinity (10 nM to 1 microM). Wild type SDCL at higher concentrations inhibited RyR1. In contrast, SDCLAFP-PTT and SDCLA-P inhibited the channels at >or=10 nM. The inhibitory actions of these two skeletal loop mutants were distinctly different from the cardiac II-III loop (CDCL) which, like the wild-type SDCL, activated channels. In contrast to the full loop, the triple A739P, F741T and P742T mutation in peptide CS converted the peptides' function from skeletal-like to cardiac-like. The individual A739P mutation, but not F741T or P742T, reduced the functional efficacy of CS. None of the mutations significantly altered the NMR-based secondary structure of the C residues in SDCLAFP-PTT or CS. The CS peptide and its mutants, like the cardiac CC peptide, were all partially alpha helical at low temperatures. The results show that residue A739 is critical for the functional consequences of interactions between RyR1 and either the skeletal II-III loop or CS, but that none of A739, F741 or P742 are critical determinants of the structure of the C region.
- Published
- 2005
- Full Text
- View/download PDF
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