1
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Thomson AL, Robinson AJ, Belgi A. Synthesis of Cystine-Stabilised Dicarba Conotoxin EpI: Ring-Closing Metathesis of Sidechain Deprotected, Sulfide-Rich Sequences. Mar Drugs 2023; 21:390. [PMID: 37504921 PMCID: PMC10381330 DOI: 10.3390/md21070390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 06/22/2023] [Accepted: 06/27/2023] [Indexed: 07/29/2023] Open
Abstract
Recombinant peptide synthesis allows for large-scale production of peptides with therapeutic potential. However, access to dicarba peptidomimetics via sidechain-deprotected sequences becomes challenging with exposed Lewis basicity presented by amine and sulfur-containing residues. Presented here is a combination of strategies which can be used to deactivate coordinative residues and achieve high-yielding Ru-catalyzed ring-closing metathesis. The chemistry is exemplified using α-conotoxin EpI, a native bicyclic disulfide-containing sequence isolated from the marine conesnail Conus episcopatus. Replacement of the loop I disulfide with E/Z-dicarba bridges was achieved with high conversion via solution-phase ring-closing metathesis of the unprotected linear peptide after simple chemoselective oxidation and ion-exchange masking of problematic functionality. Metathesis was also attempted in green solvent choices to further improve the sustainability of dicarba peptide synthesis.
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Affiliation(s)
- Amy L Thomson
- School of Chemistry, Monash University, Clayton, VIC 3800, Australia
| | - Andrea J Robinson
- School of Chemistry, Monash University, Clayton, VIC 3800, Australia
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton, VIC 3800, Australia
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2
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Thomson AL, Gleeson EC, Belgi A, Jackson WR, Izgorodina EI, Robinson AJ. Negating coordinative cysteine and methionine residues during metathesis of unprotected peptides. Chem Commun (Camb) 2023. [PMID: 37200079 DOI: 10.1039/d3cc01476b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Ru-Alkylidene catalysed olefin metathesis generates metabolically stable cystine bridge peptidomimetics with defined geometry. Deleterious coordinative bonding to the catalyst by sulfur-containing functionality found in cysteine and methionine residues can be negated by in situ and reversible oxidation of thiol and thioether functionality, as disulfides and S-oxides respectively, to facilitate high yielding ring-closing and cross metathesis of bioorthogonally protected peptides.
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Affiliation(s)
- Amy L Thomson
- School of Chemistry, Monash University, Clayton 3800, Victoria, Australia.
| | - Ellen C Gleeson
- School of Chemistry, Monash University, Clayton 3800, Victoria, Australia.
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton 3800, Victoria, Australia.
| | - W Roy Jackson
- School of Chemistry, Monash University, Clayton 3800, Victoria, Australia.
| | | | - Andrea J Robinson
- School of Chemistry, Monash University, Clayton 3800, Victoria, Australia.
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3
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Krishnarjuna B, Sunanda P, Seow J, Tae HS, Robinson SD, Belgi A, Robinson AJ, Safavi-Hemami H, Adams DJ, Norton RS. Characterisation of Elevenin-Vc1 from the Venom of Conus victoriae: A Structural Analogue of α-Conotoxins. Mar Drugs 2023; 21:md21020081. [PMID: 36827123 PMCID: PMC9963005 DOI: 10.3390/md21020081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 01/12/2023] [Accepted: 01/23/2023] [Indexed: 01/27/2023] Open
Abstract
Elevenins are peptides found in a range of organisms, including arthropods, annelids, nematodes, and molluscs. They consist of 17 to 19 amino acid residues with a single conserved disulfide bond. The subject of this study, elevenin-Vc1, was first identified in the venom of the cone snail Conus victoriae (Gen. Comp. Endocrinol. 2017, 244, 11-18). Although numerous elevenin sequences have been reported, their physiological function is unclear, and no structural information is available. Upon intracranial injection in mice, elevenin-Vc1 induced hyperactivity at doses of 5 or 10 nmol. The structure of elevenin-Vc1, determined using nuclear magnetic resonance spectroscopy, consists of a short helix and a bend region stabilised by the single disulfide bond. The elevenin-Vc1 structural fold is similar to that of α-conotoxins such as α-RgIA and α-ImI, which are also found in the venoms of cone snails and are antagonists at specific subtypes of nicotinic acetylcholine receptors (nAChRs). In an attempt to mimic the functional motif, Asp-Pro-Arg, of α-RgIA and α-ImI, we synthesised an analogue, designated elevenin-Vc1-DPR. However, neither elevenin-Vc1 nor the analogue was active at six different human nAChR subtypes (α1β1εδ, α3β2, α3β4, α4β2, α7, and α9α10) at 1 µM concentrations.
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Affiliation(s)
- Bankala Krishnarjuna
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Punnepalli Sunanda
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Jeffrey Seow
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Han-Shen Tae
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW 2522, Australia
| | - Samuel D. Robinson
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton, VIC 3800, Australia
| | | | | | - David J. Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW 2522, Australia
| | - Raymond S. Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
- Correspondence: ; Tel.: +61-3-9903-9167
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4
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Ong SC, Belgi A, Merriman AL, Delaine CA, van Lierop B, Andrikopoulos S, Robinson AJ, Forbes BE. Minimizing Mitogenic Potency of Insulin Analogues Through Modification of a Disulfide Bond. Front Endocrinol (Lausanne) 2022; 13:907864. [PMID: 35832429 PMCID: PMC9271792 DOI: 10.3389/fendo.2022.907864] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 05/09/2022] [Indexed: 11/13/2022] Open
Abstract
The mechanisms by which insulin activates the insulin receptor to promote metabolic processes and cellular growth are still not clear. Significant advances have been gained from recent structural studies in understanding how insulin binds to its receptor. However, the way in which specific interactions lead to either metabolic or mitogenic signalling remains unknown. Currently there are only a few examples of insulin receptor agonists that have biased signalling properties. Here we use novel insulin analogues that differ only in the chemical composition at the A6-A11 bond, as it has been changed to a rigid, non-reducible C=C linkage (dicarba bond), to reveal mechanisms underlying signaling bias. We show that introduction of an A6-A11 cis-dicarba bond into either native insulin or the basal/long acting insulin glargine results in biased signalling analogues with low mitogenic potency. This can be attributed to reduced insulin receptor activation that prevents effective receptor internalization and mitogenic signalling. Insight gained into the receptor interactions affected by insertion of an A6-A11 cis-dicarba bond will ultimately assist in the development of new insulin analogues for the treatment of diabetes that confer low mitogenic activity and therefore pose minimal risk of promoting cancer with long term use.
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Affiliation(s)
- Shee Chee Ong
- Discipline of Medical Biochemistry, Flinders Health and Medical Research Institute, Flinders University of South Australia, Bedford Park, SA, Australia
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton, VIC, Australia
| | - Allanah L. Merriman
- Discipline of Medical Biochemistry, Flinders Health and Medical Research Institute, Flinders University of South Australia, Bedford Park, SA, Australia
| | - Carlie A. Delaine
- Discipline of Medical Biochemistry, Flinders Health and Medical Research Institute, Flinders University of South Australia, Bedford Park, SA, Australia
| | | | | | | | - Briony E. Forbes
- Discipline of Medical Biochemistry, Flinders Health and Medical Research Institute, Flinders University of South Australia, Bedford Park, SA, Australia
- *Correspondence: Briony E. Forbes,
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5
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Belgi A, Burnley JV, MacRaild CA, Chhabra S, Elnahriry KA, Robinson SD, Gooding SG, Tae HS, Bartels P, Sadeghi M, Zhao FY, Wei H, Spanswick D, Adams DJ, Norton RS, Robinson AJ. Alkyne-Bridged α-Conotoxin Vc1.1 Potently Reverses Mechanical Allodynia in Neuropathic Pain Models. J Med Chem 2021; 64:3222-3233. [PMID: 33724033 DOI: 10.1021/acs.jmedchem.0c02151] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Several Conus-derived venom peptides are promising lead compounds for the management of neuropathic pain, with α-conotoxins being of particular interest. Modification of the interlocked disulfide framework of α-conotoxin Vc1.1 has been achieved using on-resin alkyne metathesis. Although introduction of a metabolically stable alkyne motif significantly disrupts backbone topography, the structural modification generates a potent and selective GABAB receptor agonist that inhibits Cav2.2 channels and exhibits dose-dependent reversal of mechanical allodynia in a behavioral rat model of neuropathic pain. The findings herein support the hypothesis that analgesia can be achieved via activation of GABABRs expressed in dorsal root ganglion (DRG) sensory neurons.
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Affiliation(s)
- Alessia Belgi
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - James V Burnley
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Christopher A MacRaild
- Medicinal Chemistry, Monash Institute of Pharmaceutical Science, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Sandeep Chhabra
- Medicinal Chemistry, Monash Institute of Pharmaceutical Science, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Khaled A Elnahriry
- Medicinal Chemistry, Monash Institute of Pharmaceutical Science, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Samuel D Robinson
- Medicinal Chemistry, Monash Institute of Pharmaceutical Science, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Simon G Gooding
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Han-Shen Tae
- Illawarra Health & Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Peter Bartels
- Illawarra Health & Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Mahsa Sadeghi
- Illawarra Health & Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia
| | | | | | - David Spanswick
- NeuroSolutions Ltd., Coventry CV4 7AL, U.K
- Biomedicine Discovery Institute and the Department of Physiology, Monash University, Clayton, Victoria 3800, Australia
- Warwick Medical School, University of Warwick, Coventry CV4 7AL, U.K
| | - David J Adams
- Illawarra Health & Medical Research Institute (IHMRI), University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Science, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
- ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria 3052, Australia
| | - Andrea J Robinson
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
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6
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Kennedy AC, Belgi A, Husselbee BW, Spanswick D, Norton RS, Robinson AJ. α-Conotoxin Peptidomimetics: Probing the Minimal Binding Motif for Effective Analgesia. Toxins (Basel) 2020; 12:E505. [PMID: 32781580 PMCID: PMC7472027 DOI: 10.3390/toxins12080505] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/29/2020] [Accepted: 08/03/2020] [Indexed: 12/18/2022] Open
Abstract
Several analgesic α-conotoxins have been isolated from marine cone snails. Structural modification of native peptides has provided potent and selective analogues for two of its known biological targets-nicotinic acetylcholine and γ-aminobutyric acid (GABA) G protein-coupled (GABAB) receptors. Both of these molecular targets are implicated in pain pathways. Despite their small size, an incomplete understanding of the structure-activity relationship of α-conotoxins at each of these targets has hampered the development of therapeutic leads. This review scrutinises the N-terminal domain of the α-conotoxin family of peptides, a region defined by an invariant disulfide bridge, a turn-inducing proline residue and multiple polar sidechain residues, and focusses on structural features that provide analgesia through inhibition of high-voltage-activated Ca2+ channels. Elucidating the bioactive conformation of this region of these peptides may hold the key to discovering potent drugs for the unmet management of debilitating chronic pain associated with a wide range of medical conditions.
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Affiliation(s)
- Adam C. Kennedy
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia; (A.C.K.); (A.B.); (B.W.H.)
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia; (A.C.K.); (A.B.); (B.W.H.)
| | - Benjamin W. Husselbee
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia; (A.C.K.); (A.B.); (B.W.H.)
| | - David Spanswick
- Biomedicine Discovery Institute and the Department of Physiology, Monash University, Victoria 3800, Australia;
- Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
- NeuroSolutions Ltd., Coventry CV4 7AL, UK
| | - Raymond S. Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Science, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia;
- ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria 3052, Australia
| | - Andrea J. Robinson
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia; (A.C.K.); (A.B.); (B.W.H.)
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7
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Ong SC, Belgi A, van Lierop B, Delaine C, Andrikopoulos S, MacRaild CA, Norton RS, Haworth NL, Robinson AJ, Forbes BE. Probing the correlation between insulin activity and structural stability through introduction of the rigid A6-A11 bond. J Biol Chem 2018; 293:11928-11943. [PMID: 29899115 DOI: 10.1074/jbc.ra118.002486] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/10/2018] [Indexed: 11/06/2022] Open
Abstract
The development of fast-acting and highly stable insulin analogues is challenging. Insulin undergoes structural transitions essential for binding and activation of the insulin receptor (IR), but these conformational changes can also affect insulin stability. Previously, we substituted the insulin A6-A11 cystine with a rigid, non-reducible C=C linkage ("dicarba" linkage). A cis-alkene permitted the conformational flexibility of the A-chain N-terminal helix necessary for high-affinity IR binding, resulting in surprisingly rapid activity in vivo Here, we show that, unlike the rapidly acting LysB28ProB29 insulin analogue (KP insulin), cis-dicarba insulin is not inherently monomeric. We also show that cis-dicarba KP insulin lowers blood glucose levels even more rapidly than KP insulin, suggesting that an inability to oligomerize is not responsible for the observed rapid activity onset of cis-dicarba analogues. Although rapid-acting, neither dicarba species is stable, as assessed by fibrillation and thermodynamics assays. MALDI analyses and molecular dynamics simulations of cis-dicarba insulin revealed a previously unidentified role of the A6-A11 linkage in insulin conformational dynamics. By controlling the conformational flexibility of the insulin B-chain helix, this linkage affects overall insulin structural stability. This effect is independent of its regulation of the A-chain N-terminal helix flexibility necessary for IR engagement. We conclude that high-affinity IR binding, rapid in vivo activity, and insulin stability can be regulated by the specific conformational arrangement of the A6-A11 linkage. This detailed understanding of insulin's structural dynamics may aid in the future design of rapid-acting insulin analogues with improved stability.
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Affiliation(s)
- Shee Chee Ong
- From the College of Medicine and Public Health, Flinders University of South Australia, Bedford Park, South Australia 5042, Australia
| | - Alessia Belgi
- the School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Bianca van Lierop
- the School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Carlie Delaine
- From the College of Medicine and Public Health, Flinders University of South Australia, Bedford Park, South Australia 5042, Australia
| | - Sofianos Andrikopoulos
- the Department of Medicine, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Christopher A MacRaild
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Naomi L Haworth
- the School of Chemistry, Monash University, Clayton, Victoria 3800, Australia.,the Research School of Chemistry, Australian National University, Acton, Australian Capital Territory 2601, Australia, and.,the School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3216, Australia
| | - Andrea J Robinson
- the School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Briony E Forbes
- From the College of Medicine and Public Health, Flinders University of South Australia, Bedford Park, South Australia 5042, Australia,
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8
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van Lierop B, Ong SC, Belgi A, Delaine C, Andrikopoulos S, Haworth NL, Menting JG, Lawrence MC, Robinson AJ, Forbes BE. Insulin in motion: The A6-A11 disulfide bond allosterically modulates structural transitions required for insulin activity. Sci Rep 2017; 7:17239. [PMID: 29222417 PMCID: PMC5722942 DOI: 10.1038/s41598-017-16876-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/17/2017] [Indexed: 01/10/2023] Open
Abstract
The structural transitions required for insulin to activate its receptor and initiate regulation of glucose homeostasis are only partly understood. Here, using ring-closing metathesis, we substitute the A6-A11 disulfide bond of insulin with a rigid, non-reducible dicarba linkage, yielding two distinct stereo-isomers (cis and trans). Remarkably, only the cis isomer displays full insulin potency, rapidly lowering blood glucose in mice (even under insulin-resistant conditions). It also posseses reduced mitogenic activity in vitro. Further biophysical, crystallographic and molecular-dynamics analyses reveal that the A6-A11 bond configuration directly affects the conformational flexibility of insulin A-chain N-terminal helix, dictating insulin’s ability to engage its receptor. We reveal that in native insulin, contraction of the Cα-Cα distance of the flexible A6-A11 cystine allows the A-chain N-terminal helix to unwind to a conformation that allows receptor engagement. This motion is also permitted in the cis isomer, with its shorter Cα-Cα distance, but prevented in the extended trans analogue. These findings thus illuminate for the first time the allosteric role of the A6-A11 bond in mediating the transition of the hormone to an active conformation, significantly advancing our understanding of insulin action and opening up new avenues for the design of improved therapeutic analogues.
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Affiliation(s)
- Bianca van Lierop
- School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia
| | - Shee Chee Ong
- College of Medicine & Public Health, Flinders University of South Australia, Bedford Park, 5042, Australia
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia
| | - Carlie Delaine
- College of Medicine & Public Health, Flinders University of South Australia, Bedford Park, 5042, Australia
| | | | - Naomi L Haworth
- School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia.,Research School of Chemistry, Australian National University, Acton, ACT 2601, Australia.,School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria, 3216, Australia
| | - John G Menting
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria, 3052, Australia
| | - Michael C Lawrence
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria, 3052, Australia.,Department of Medical Biology, University of Melbourne, Royal Parade, Parkville, Victoria, 3050, Australia
| | - Andrea J Robinson
- School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia.
| | - Briony E Forbes
- College of Medicine & Public Health, Flinders University of South Australia, Bedford Park, 5042, Australia.
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9
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Drane SB, Robinson SD, MacRaild CA, Chhabra S, Chittoor B, Morales RAV, Leung EWW, Belgi A, Espino SS, Olivera BM, Robinson AJ, Chalmers DK, Norton RS. Structure and activity of contryphan-Vc2: Importance of the d-amino acid residue. Toxicon 2017; 129:113-122. [PMID: 28216409 DOI: 10.1016/j.toxicon.2017.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/11/2017] [Accepted: 02/16/2017] [Indexed: 01/19/2023]
Abstract
In natural proteins and peptides, amino acids exist almost invariably as l-isomers. There are, however, several examples of naturally-occurring peptides containing d-amino acids. In this study we investigated the role of a naturally-occurring d-amino acid in a small peptide identified in the transcriptome of a marine cone snail. This peptide belongs to a family of peptides known as contryphans, all of which contain a single d-amino acid residue. The solution structure of this peptide was solved by NMR, but further investigations with molecular dynamics simulations suggest that its solution behaviour may be more dynamic than suggested by the NMR ensemble. Functional tests in mice uncovered a novel bioactivity, a depressive phenotype that contrasts with the hyperactive phenotypes typically induced by contryphans. Trp3 is important for bioactivity, but this role is independent of the chirality at this position. The d-chirality of Trp3 in this peptide was found to be protective against enzymatic degradation. Analysis by NMR and molecular dynamics simulations indicated an interaction of Trp3 with lipid membranes, suggesting the possibility of a membrane-mediated mechanism of action for this peptide.
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Affiliation(s)
- Stephen B Drane
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Samuel D Robinson
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Christopher A MacRaild
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Sandeep Chhabra
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Balasubramanyam Chittoor
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Rodrigo A V Morales
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Eleanor W W Leung
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton 3800, Victoria, Australia
| | - Samuel S Espino
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | | | - Andrea J Robinson
- School of Chemistry, Monash University, Clayton 3800, Victoria, Australia
| | - David K Chalmers
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.
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10
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Robinson SD, Chhabra S, Belgi A, Chittoor B, Safavi-Hemami H, Robinson AJ, Papenfuss AT, Purcell AW, Norton RS. A Naturally Occurring Peptide with an Elementary Single Disulfide-Directed β-Hairpin Fold. Structure 2016; 24:293-9. [PMID: 26774129 DOI: 10.1016/j.str.2015.11.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 11/11/2015] [Accepted: 11/23/2015] [Indexed: 10/22/2022]
Abstract
Certain peptide folds, owing to a combination of intrinsic stability and resilience to amino acid substitutions, are particularly effective for the display of diverse functional groups. Such "privileged scaffolds" are valuable as starting points for the engineering of new bioactive molecules. We have identified a precursor peptide expressed in the venom gland of the marine snail Conus victoriae, which appears to belong to a hitherto undescribed class of molluscan neuropeptides. Mass spectrometry matching with the venom confirmed the complete mature peptide sequence as a 31-residue peptide with a single disulfide bond. Solution structure determination revealed a unique peptide fold that we have designated the single disulfide-directed β hairpin (SDH). The SDH fold is highly resistant to thermal denaturation and forms the core of several other multiple disulfide-containing peptide folds, including the inhibitor cystine knot. This elementary fold may offer a valuable starting point for the design and engineering of new bioactive peptides.
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Affiliation(s)
- Samuel D Robinson
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Sandeep Chhabra
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton, VIC 3800, Australia
| | - Balasubramanyam Chittoor
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | | | - Andrea J Robinson
- School of Chemistry, Monash University, Clayton, VIC 3800, Australia
| | - Anthony T Papenfuss
- Bioinformatics Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
| | - Anthony W Purcell
- The Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, VIC 3800, Australia
| | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia.
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11
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Chhabra S, Belgi A, Bartels P, van Lierop BJ, Robinson SD, Kompella SN, Hung A, Callaghan BP, Adams DJ, Robinson AJ, Norton RS. Dicarba analogues of α-conotoxin RgIA. Structure, stability, and activity at potential pain targets. J Med Chem 2014; 57:9933-44. [PMID: 25393758 DOI: 10.1021/jm501126u] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
α-Conotoxin RgIA is both an antagonist of the α9α10 nicotinic acetylcholine receptor (nAChR) subtype and an inhibitor of high-voltage-activated N-type calcium channel currents. RgIA has therapeutic potential for the treatment of pain, but reduction of the disulfide bond framework under physiological conditions represents a potential liability for clinical applications. We synthesized four RgIA analogues that replaced native disulfide pairs with nonreducible dicarba bridges. Solution structures were determined by NMR, activity assessed against biological targets, and stability evaluated in human serum. [3,12]-Dicarba analogues retained inhibition of ACh-evoked currents at α9α10 nAChRs but not N-type calcium channel currents, whereas [2,8]-dicarba analogues displayed the opposite pattern of selectivity. The [2,8]-dicarba RgIA analogues were effective in HEK293 cells stably expressing human Cav2.2 channels and transfected with human GABAB receptors. The analogues also exhibited improved serum stability over the native peptide. These selectively acting dicarba analogues may represent mechanistic probes to explore analgesia-related biological receptors.
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Affiliation(s)
- Sandeep Chhabra
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University , 381 Royal Parade, Parkville 3052, Victoria Australia
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12
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Belgi A, Bathgate RAD, Kocan M, Patil N, Zhang S, Tregear GW, Wade JD, Hossain MA. Minimum active structure of insulin-like peptide 5. J Med Chem 2013; 56:9509-16. [PMID: 24188028 DOI: 10.1021/jm400924p] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Insulin-like peptide 5 (INSL5) is a complex two-chain peptide hormone constrained by three disulfide bonds in a pattern identical to insulin. High expression of INSL5 in the colon suggests roles in activation of colon motility and appetite control. A more recent study indicates it may have significant roles in the regulation of insulin secretion and β-cell homeostasis. This peptide thus has considerable potential for the treatment of eating disorders, obesity, and/or diabetes. However, the synthesis of INSL5 is extremely challenging either by chemical or recombinant means. The A-chain is very poorly soluble and the B-chain is highly aggregating in nature which, together, makes their postsynthesis handling and purification very difficult. Given these difficulties, we have developed a highly active INSL5 analogue that has a much simpler structure with two disulfide bonds and is thus easier to assemble compared to native INSL5. This minimized peptide represents an attractive new mimetic for investigating the functional role of INSL5.
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Affiliation(s)
- Alessia Belgi
- Florey Institute of Neuroscience and Mental Health, ‡Department of Biochemistry and Molecular Biology, §Florey Department of Neuroscience and Mental Health, and ∥School of Chemistry, The University of Melbourne , Victoria 3010, Australia
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13
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Kompella S, van Lierop B, Robinson S, Belgi A, Callaghan B, Hung A, MacRaild C, Norton R, Robinson A, Adams D. Dicarba modification of α-conotoxin RgIA conferring selectivity towards α9α10 nicotinic acetylcholine receptors. Biochem Pharmacol 2013. [DOI: 10.1016/j.bcp.2013.08.043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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van Lierop BJ, Robinson SD, Kompella SN, Belgi A, McArthur JR, Hung A, MacRaild CA, Adams DJ, Norton RS, Robinson AJ. Dicarba α-conotoxin Vc1.1 analogues with differential selectivity for nicotinic acetylcholine and GABAB receptors. ACS Chem Biol 2013; 8:1815-21. [PMID: 23768016 DOI: 10.1021/cb4002393] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Conotoxins have emerged as useful leads for the development of novel therapeutic analgesics. These peptides, isolated from marine molluscs of the genus Conus, have evolved exquisite selectivity for receptors and ion channels of excitable tissue. One such peptide, α-conotoxin Vc1.1, is a 16-mer possessing an interlocked disulfide framework. Despite its emergence as a potent analgesic lead, the molecular target and mechanism of action of Vc1.1 have not been elucidated to date. In this paper we describe the regioselective synthesis of dicarba analogues of Vc1.1 using olefin metathesis. The ability of these peptides to inhibit acetylcholine-evoked current at rat α9α10 and α3β4 nicotinic acetylcholine receptors (nAChR) expressed in Xenopus oocytes has been assessed in addition to their ability to inhibit high voltage-activated (HVA) calcium channel current in isolated rat DRG neurons. Their solution structures were determined by NMR spectroscopy. Significantly, we have found that regioselective replacement of the native cystine framework with a dicarba bridge can be used to selectively tune the cyclic peptide's innate biological activity for one receptor over another. The 2,8-dicarba Vc1.1 isomer retains activity at γ-aminobutyric acid (GABAB) G protein-coupled receptors, whereas the isomeric 3,16-dicarba Vc1.1 peptide retains activity at the α9α10 nAChR subtype. These singularly acting analogues will enable the elucidation of the biological target responsible for the peptide's potent analgesic activity.
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Affiliation(s)
| | - Samuel D. Robinson
- Medicinal Chemistry, Monash
Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Shiva N. Kompella
- Health Innovations Research Institute, RMIT University, Bundoora 3083, Victoria, Australia
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton 3800, Victoria, Australia
| | - Jeffrey R. McArthur
- Health Innovations Research Institute, RMIT University, Bundoora 3083, Victoria, Australia
| | - Andrew Hung
- Health Innovations Research Institute, RMIT University, Bundoora 3083, Victoria, Australia
| | - Christopher A. MacRaild
- Medicinal Chemistry, Monash
Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - David J. Adams
- Health Innovations Research Institute, RMIT University, Bundoora 3083, Victoria, Australia
| | - Raymond S. Norton
- Medicinal Chemistry, Monash
Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Andrea J. Robinson
- School of Chemistry, Monash University, Clayton 3800, Victoria, Australia
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Shabanpoor F, Bathgate RA, Belgi A, Chan LJ, Nair VB, Wade JD, Hossain MA. Site-specific conjugation of a lanthanide chelator and its effects on the chemical synthesis and receptor binding affinity of human relaxin-2 hormone. Biochem Biophys Res Commun 2012; 420:253-6. [DOI: 10.1016/j.bbrc.2012.02.141] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 02/24/2012] [Indexed: 12/24/2022]
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Shabanpoor F, Akhter Hossain M, Ryan PJ, Belgi A, Layfield S, Kocan M, Zhang S, Samuel CS, Gundlach AL, Bathgate RAD, Separovic F, Wade JD. Minimization of human relaxin-3 leading to high-affinity analogues with increased selectivity for relaxin-family peptide 3 receptor (RXFP3) over RXFP1. J Med Chem 2012; 55:1671-81. [PMID: 22257012 DOI: 10.1021/jm201505p] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Relaxin-3 is a neuropeptide that is implicated in the regulation of stress responses and memory. The elucidation of its precise physiological role(s) has, however, been hampered by cross-activation of the relaxin-2 receptor, RXFP1, in the brain. The current study undertook to develop analogues of human relaxin-3 (H3 relaxin) that can selectively bind and activate its receptor, RXFP3. We developed a high-affinity selective agonist (analogue 2) by removal of the intra-A chain disulfide bond and deletion of 10 residues from the N terminus of the A chain. Further truncation of this analogue from the C terminus of the B chain to Cys(B22) and addition of an Arg(B23) led to a high-affinity, RXFP3-selective, competitive antagonist (analogue 3). Central administration of analogue 2 in rats increased food intake, which was blocked by prior coadministration of analogue 3. These novel RXFP3-selective peptides represent valuable pharmacological tools to study the physiological roles of H3 relaxin/RXFP3 systems in the brain and important leads for the development of novel compounds for the treatment of affective and cognitive disorders.
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Affiliation(s)
- Fazel Shabanpoor
- Florey Neuroscience Institutes, The University of Melbourne, Victoria 3010, Australia
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Belgi A, Hossain MA, Shabanpoor F, Chan L, Zhang S, Bathgate RAD, Tregear GW, Wade JD. Structure and Function Relationship of Murine Insulin-like Peptide 5 (INSL5): Free C-Terminus Is Essential for RXFP4 Receptor Binding and Activation. Biochemistry 2011; 50:8352-61. [DOI: 10.1021/bi201093m] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alessia Belgi
- Florey
Neuroscience Institutes, ‡Department of Biochemistry and Molecular Biology, and §School of Chemistry, The University of Melbourne, Victoria
3010, Australia
| | - Mohammed A. Hossain
- Florey
Neuroscience Institutes, ‡Department of Biochemistry and Molecular Biology, and §School of Chemistry, The University of Melbourne, Victoria
3010, Australia
| | - Fazel Shabanpoor
- Florey
Neuroscience Institutes, ‡Department of Biochemistry and Molecular Biology, and §School of Chemistry, The University of Melbourne, Victoria
3010, Australia
| | - Linda Chan
- Florey
Neuroscience Institutes, ‡Department of Biochemistry and Molecular Biology, and §School of Chemistry, The University of Melbourne, Victoria
3010, Australia
| | - Suode Zhang
- Florey
Neuroscience Institutes, ‡Department of Biochemistry and Molecular Biology, and §School of Chemistry, The University of Melbourne, Victoria
3010, Australia
| | - Ross A. D. Bathgate
- Florey
Neuroscience Institutes, ‡Department of Biochemistry and Molecular Biology, and §School of Chemistry, The University of Melbourne, Victoria
3010, Australia
| | - Geoffrey W. Tregear
- Florey
Neuroscience Institutes, ‡Department of Biochemistry and Molecular Biology, and §School of Chemistry, The University of Melbourne, Victoria
3010, Australia
| | - John D. Wade
- Florey
Neuroscience Institutes, ‡Department of Biochemistry and Molecular Biology, and §School of Chemistry, The University of Melbourne, Victoria
3010, Australia
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18
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Yalçin H, Karayalçin B, Boz A, Talay B, Belgi A, Yalçin F. Contractility evaluation by 2 dimensional echocardiography and gated SPECT myocardial perfusion scintigraphy in hypertensive patients with clinical presentation of atypical chest pain. Hippokratia 2011; 15:64-68. [PMID: 21607039 PMCID: PMC3093148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
BACKGROUND Hypertension (HT) is a growing health problem in the population and associated with increased cardiovascular event risk and mortality. In hypertensive patients, progressive left ventricular (LV) contractility deterioration is detectable by gated single photon emission computed tomography (SPECT) myocardial perfusion scintigraphy9. We planned this study to explore the agreement in ejection fraction (EF) determination between 2 dimensional echocardiography and gated SPECT analysis in selected group of patients with hypertension. PATIENTS AND METHODS We studied 26 consecutive patients (mean age 56.5 ± 8.8 years; 6 men) with hypertension. Quantitative contractility analysis by both echocardiography and SPECT at rest was performed to investigate the agreement between two diagnostic tests. RESULTS EF at rest was greater than 55 % in all patients. All patients had a clinical presentation of atypical chest pain. Therefore, in addition to quantitative contractility analysis at rest by echocardiography and myocardial SPECT perfusion scintigraphy, we examined ischemia by stress induction and determined that 10 patients had ischemic finding (38.4 %). The mean value of EF calculated by echocardiography was 67.5 ± 5.7 %, while EF by gated SPECT was 72.8 ± 8.5 %. We documented an acceptable agreement in EF determination between these 2 diagnostic tests by meaningful correlation (r = 0.556, p = 0.003). There was no regional contractility deterioration despite existence of ischemia in 10 patients of the study group. CONCLUSIONS We observed that both echocardiography and gated SPECT can be used for quantification of EF in the hypertensive patients with an acceptable agreement.
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Aydemir M, Yazisiz V, Basarici I, Avci AB, Erbasan F, Belgi A, Terzioglu E. Cardiac autonomic profile in rheumatoid arthritis and systemic lupus erythematosus. Lupus 2009; 19:255-61. [PMID: 20015916 DOI: 10.1177/0961203309351540] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Neurological involvement is a well-documented issue in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). However, little is known about the involvement of the autonomic nervous system. This study was conducted to investigate autonomic nervous system dysfunction in patients with RA and SLE. Twenty-six RA patients, 38 SLE patients and 40 healthy controls were recruited from our in- and out-patient departments. Heart rate variability (HRV) parameters (the power of the high- [HF] and low-frequency [LF] band of haemodynamic time series, the ratio between low- and high-frequency components [LF/HF ratio], the power spectral density), baroreflex sensitivity (BRS) and beat-to-beat blood pressures were assessed by a novel non-invasive haemodynamic monitoring tool (Task Force Monitor [TFM], CNSystems Medizintechnik GmbH, Graz, Austria). Autonomic nervous system dysfunction was determined according to classical Ewing autonomic test battery. Furthermore, we implemented a secondary autonomic test score by modifying the Ewing test battery with additional criteria. Both the classical and modified Ewing test batteries have revealed that the frequencies of autonomic neuropathy were significantly higher in patient groups compared with controls (p < 0.001). Evaluation by TFM revealed that deterioration of sophisticated autonomic parameters (such as HRV and BRS) were more pronounced in the patient groups compared with controls. There was a significant association between BRS and Ewing test scores and abnormal BRS results were more frequent in patients with autonomic dysfunction according to Ewing test batteries. No relation was found between autonomic neuropathy and disease duration, disease activity and autoantibody positivity. Consequently, we believe that further large-scale studies investigating cardiovascular autonomic neuropathy in rheumatic diseases should be carried out to verify our findings and manifest clinical consequences beyond these results.
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Affiliation(s)
- M Aydemir
- Carşamba Government Hospital, Carşamba, Samsun, Turkey
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Hossain MA, Belgi A, Lin F, Zhang S, Shabanpoor F, Chan L, Belyea C, Truong HT, Blair AR, Andrikopoulos S, Tregear GW, Wade JD. Use of a Temporary “Solubilizing” Peptide Tag for the Fmoc Solid-Phase Synthesis of Human Insulin Glargine via Use of Regioselective Disulfide Bond Formation. Bioconjug Chem 2009; 20:1390-6. [DOI: 10.1021/bc900181a] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mohammed Akhter Hossain
- Howard Florey Institute, Department of Biochemistry and Molecular Biology, School of Chemistry, Department of Medicine (AH/NH), The University of Melbourne, Victoria 3010, Australia, and Metabolic Pharmaceuticals Ltd, 2/320 Lorimer Street, Port Melbourne, Victoria 3207, Australia
| | - Alessia Belgi
- Howard Florey Institute, Department of Biochemistry and Molecular Biology, School of Chemistry, Department of Medicine (AH/NH), The University of Melbourne, Victoria 3010, Australia, and Metabolic Pharmaceuticals Ltd, 2/320 Lorimer Street, Port Melbourne, Victoria 3207, Australia
| | - Feng Lin
- Howard Florey Institute, Department of Biochemistry and Molecular Biology, School of Chemistry, Department of Medicine (AH/NH), The University of Melbourne, Victoria 3010, Australia, and Metabolic Pharmaceuticals Ltd, 2/320 Lorimer Street, Port Melbourne, Victoria 3207, Australia
| | - Suode Zhang
- Howard Florey Institute, Department of Biochemistry and Molecular Biology, School of Chemistry, Department of Medicine (AH/NH), The University of Melbourne, Victoria 3010, Australia, and Metabolic Pharmaceuticals Ltd, 2/320 Lorimer Street, Port Melbourne, Victoria 3207, Australia
| | - Fazel Shabanpoor
- Howard Florey Institute, Department of Biochemistry and Molecular Biology, School of Chemistry, Department of Medicine (AH/NH), The University of Melbourne, Victoria 3010, Australia, and Metabolic Pharmaceuticals Ltd, 2/320 Lorimer Street, Port Melbourne, Victoria 3207, Australia
| | - Linda Chan
- Howard Florey Institute, Department of Biochemistry and Molecular Biology, School of Chemistry, Department of Medicine (AH/NH), The University of Melbourne, Victoria 3010, Australia, and Metabolic Pharmaceuticals Ltd, 2/320 Lorimer Street, Port Melbourne, Victoria 3207, Australia
| | - Chris Belyea
- Howard Florey Institute, Department of Biochemistry and Molecular Biology, School of Chemistry, Department of Medicine (AH/NH), The University of Melbourne, Victoria 3010, Australia, and Metabolic Pharmaceuticals Ltd, 2/320 Lorimer Street, Port Melbourne, Victoria 3207, Australia
| | - Hue-Trung Truong
- Howard Florey Institute, Department of Biochemistry and Molecular Biology, School of Chemistry, Department of Medicine (AH/NH), The University of Melbourne, Victoria 3010, Australia, and Metabolic Pharmaceuticals Ltd, 2/320 Lorimer Street, Port Melbourne, Victoria 3207, Australia
| | - Amy R. Blair
- Howard Florey Institute, Department of Biochemistry and Molecular Biology, School of Chemistry, Department of Medicine (AH/NH), The University of Melbourne, Victoria 3010, Australia, and Metabolic Pharmaceuticals Ltd, 2/320 Lorimer Street, Port Melbourne, Victoria 3207, Australia
| | - Sof Andrikopoulos
- Howard Florey Institute, Department of Biochemistry and Molecular Biology, School of Chemistry, Department of Medicine (AH/NH), The University of Melbourne, Victoria 3010, Australia, and Metabolic Pharmaceuticals Ltd, 2/320 Lorimer Street, Port Melbourne, Victoria 3207, Australia
| | - Geoffrey W. Tregear
- Howard Florey Institute, Department of Biochemistry and Molecular Biology, School of Chemistry, Department of Medicine (AH/NH), The University of Melbourne, Victoria 3010, Australia, and Metabolic Pharmaceuticals Ltd, 2/320 Lorimer Street, Port Melbourne, Victoria 3207, Australia
| | - John D. Wade
- Howard Florey Institute, Department of Biochemistry and Molecular Biology, School of Chemistry, Department of Medicine (AH/NH), The University of Melbourne, Victoria 3010, Australia, and Metabolic Pharmaceuticals Ltd, 2/320 Lorimer Street, Port Melbourne, Victoria 3207, Australia
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Konstantopoulou M, Belgi A, Griffiths KD, Seale JRC, Macfarlane AW. Azathioprine-induced pancytopenia in a patient with pompholyx and deficiency of erythrocyte thiopurine methyltransferase. BMJ 2005; 330:350-1. [PMID: 15705694 PMCID: PMC548735 DOI: 10.1136/bmj.330.7487.350] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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23
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Demir I, Yilmaz H, Belgi A, Sancaktar O. [Treatment of no-reflow phenomenon with intracoronary verapamil after primary stent deployment during myocardial infarction]. Anadolu Kardiyol Derg 2001; 1:213-6. [PMID: 12101827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Affiliation(s)
- I Demir
- Akdeniz Universitesi Tip Fakültesi, Antalya.
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Yilmaz H, Demir I, Belgi A, Kabukçu M, Yalçinkaya S, Sancaktar O. Sidebranch occlusion in direct intracoronary stenting: predictors and results. J Invasive Cardiol 2001; 13:578-81. [PMID: 11481505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
We assessed the angiographic predictors and results of major (> 1 mm) sidebranch occlusion (SBO) following direct intracoronary stenting (DS) in 86 patients. The occlusion of a sidebranch is a well-defined risk after balloon angioplasty and stenting. However, the impact of direct stenting without predilatation on the coronary flow of sidebranches emerging within the stented segment has not been studied solely. A total of 111 sidebranches were analyzed. Sidebranch type, take-off angle, ostial involvement and procedural characteristics were evaluated. Nine out of 111 (8%) stent-covered sidebranches were occluded. Sidebranches with > 50% stenosis that take off within or just beyond the diseased portion of the lesion (unfavorable morphology) were the most powerful morphologic predictor of SBO (odds ratio: 8.0; 95% confidence interval: 1.5--40.8; p = 0.007). Take-off angle of the sidebranch was not found to have any effect on SBO. Post-stent dilation using high-pressure inflation (15.0 +/- 2.1 atmospheres), inflation (odds ratio: 1.1; 95% CI: 1.0--1.2; p = 0.038), and 3 times inflation (odds ratio: 4.5; 95% CI: 1.1--18.3; p = 0.023) were the procedural predictor of SBO. Of those 40 unfavorable morphologies, seven (17.5%) were occluded compared to 2.8% (2/71) of the favorable morphologies. Nine out of 9 (100%) occluded after high-pressure inflation. Three patients complained of chest pain and 1 had non-Q wave myocardial infarction attributed to SBO. These findings indicate that the incidence of SBO and complications are less than expected and has a favorable outcome in direct intracoronary stenting.
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Affiliation(s)
- H Yilmaz
- Department of Cardiology, Akdeniz University, Antalya, Turkey.
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Derebek E, Kozan O, Durak H, Ergene O, Ozbilek E, Capa G, Belgi A, Yurekli Y, Degirmenci B, Dogan S. Sublingual nitrate plus 99Tcm-tetrofosmin infusion in the detection of severely ischaemic but viable myocardium: a comparative study with stress, redistribution, reinjection and late redistribution 201Tl imaging. Nucl Med Commun 1996; 17:864-71. [PMID: 8951907 DOI: 10.1097/00006231-199610000-00007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
To investigate the role of sublingual nitrate plus 99Tcm-tetrofosmin infusion in the detection of severely ischaemic but viable myocardium, we selected 25 patients with coronary artery disease who had at least one fixed segmental defect during conventional stress-redistribution (ST-RD) 201Tl single photon emission tomographic (SPET) imaging. Reinjection (RI) and 24 h late redistribution (LRD) imaging were also performed. Within a week of 201Tl imaging, one-day rest-stress (R-ST) 99Tcm-tetrofosmin SPET was performed with the same stress levels. The following day, 99Tcm-tetrofosmin was infused over 1 h immediately after sublingual nitrate administration and SPET images (N + Inf) were acquired. Of 100 fixed defects on R-ST 99Tcm-tetrofosmin imaging, 15 were reversible on N + Inf 99Tcm-tetrofosmin imaging. There was 91% concordance between ST-RD/RI/LRD 201Tl and R-ST/N + Inf 99Tcm-tetrofosmin imaging regarding reversibility. We conclude that N + Inf 99Tcm-tetrofosmin imaging may be clinically useful in the detection of severely ischaemic but viable myocardium.
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Affiliation(s)
- E Derebek
- Department of Nuclear Medicine, School of Medicine, Dokuz Eylul University, Inciralti, Izmir, Turkey
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