1
|
Ericson MD, Freeman KT, Larson CM, Bouchard JL, John K, Lunzer MM, Koerperich ZM, Haskell-Luevano C. Incorporation of Three Extracyclic Arginine Residues into a Melanocortin Macrocyclic Agonist (c[Pro-His-DPhe-Arg-Trp-Dap-Lys(Arg-Arg-Arg-Ac)-DPro]) Decreases Food Intake When Administered Intrathecally or Subcutaneously Compared to a Macrocyclic Ligand Lacking Extracyclic Arginine Residues (c[Pro-His-DPhe-Arg-Trp-Dap-Ala-DPro)]. ACS Pharmacol Transl Sci 2024; 7:1114-1125. [PMID: 38633589 PMCID: PMC11020072 DOI: 10.1021/acsptsci.4c00011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 03/01/2024] [Accepted: 03/05/2024] [Indexed: 04/19/2024]
Abstract
Of the three Food and Drug Administration-approved melanocortin peptide drugs, two possess a cyclic scaffold, demonstrating that cyclized melanocortin peptides have therapeutic relevance. An extracyclic Arg residue, critical for pharmacological activity in the approved melanocortin cyclic drug setmelanotide, has also been demonstrated to increase the signal when fluorescently labeled cell-penetrating cyclic peptides are incubated with HeLa cells, with the maximal signal observed with three extracyclic Arg amino acids. Herein, a branching Lys residue was substituted into two macrocyclic melanocortin peptide agonists to incorporate 0-3 extracyclic Arg amino acids. Incorporation of the Arg residues resulted in equipotent or increased agonist potency at the mouse melanocortin receptors in vitro, suggesting that these substitutions were tolerated in the macrocyclic scaffolds. Further in vivo evaluation of one parent ligand (c[Pro-His-DPhe-Arg-Trp-Dap-Ala-Pro]) and the three Arg derivative (c[Pro-His-DPhe-Arg-Trp-Dap-Lys(Ac-Arg-Arg-Arg)-Pro)] demonstrated that the three Arg derivative further decreased food intake compared to the parent macrocycle when the compounds were administered either via intrathecal injection or subcutaneous dosing. This suggests that three extracyclic Arg amino acids may be beneficial in the design of cyclic melanocortin ligands and that in vitro pharmacological profiling may not predict the in vivo efficacy of melanocortin ligands.
Collapse
Affiliation(s)
- Mark D. Ericson
- Department of Medicinal Chemistry, Institute for Translational Neuroscience, University
of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Katie T. Freeman
- Department of Medicinal Chemistry, Institute for Translational Neuroscience, University
of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Courtney M. Larson
- Department of Medicinal Chemistry, Institute for Translational Neuroscience, University
of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Jacob L. Bouchard
- Department of Medicinal Chemistry, Institute for Translational Neuroscience, University
of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Kristen John
- Department of Medicinal Chemistry, Institute for Translational Neuroscience, University
of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Mary M. Lunzer
- Department of Medicinal Chemistry, Institute for Translational Neuroscience, University
of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Zoe M. Koerperich
- Department of Medicinal Chemistry, Institute for Translational Neuroscience, University
of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Carrie Haskell-Luevano
- Department of Medicinal Chemistry, Institute for Translational Neuroscience, University
of Minnesota, Minneapolis, Minnesota 55455, United States
| |
Collapse
|
2
|
Kobayashi K, Taguchi A, Cui Y, Shida H, Muguruma K, Takayama K, Taniguchi A, Hayashi Y. “On‐Resin” Disulfide Peptide Synthesis with Methyl 3‐Nitro‐2‐pyridinesulfenate. European J Org Chem 2021. [DOI: 10.1002/ejoc.202001517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Kiyotaka Kobayashi
- Department of Medicinal chemistry School of Pharmacy Tokyo University of Pharmacy and Life Sciences 1432-1 Horinouchi Hachioji, Tokyo 192–0392 Japan
| | - Akihiro Taguchi
- Department of Medicinal chemistry School of Pharmacy Tokyo University of Pharmacy and Life Sciences 1432-1 Horinouchi Hachioji, Tokyo 192–0392 Japan
| | - Yan Cui
- Department of Medicinal chemistry School of Pharmacy Tokyo University of Pharmacy and Life Sciences 1432-1 Horinouchi Hachioji, Tokyo 192–0392 Japan
| | - Hayate Shida
- Department of Medicinal chemistry School of Pharmacy Tokyo University of Pharmacy and Life Sciences 1432-1 Horinouchi Hachioji, Tokyo 192–0392 Japan
| | - Kyohei Muguruma
- Department of Medicinal chemistry School of Pharmacy Tokyo University of Pharmacy and Life Sciences 1432-1 Horinouchi Hachioji, Tokyo 192–0392 Japan
| | - Kentaro Takayama
- Department of Medicinal chemistry School of Pharmacy Tokyo University of Pharmacy and Life Sciences 1432-1 Horinouchi Hachioji, Tokyo 192–0392 Japan
| | - Atsuhiko Taniguchi
- Department of Medicinal chemistry School of Pharmacy Tokyo University of Pharmacy and Life Sciences 1432-1 Horinouchi Hachioji, Tokyo 192–0392 Japan
| | - Yoshio Hayashi
- Department of Medicinal chemistry School of Pharmacy Tokyo University of Pharmacy and Life Sciences 1432-1 Horinouchi Hachioji, Tokyo 192–0392 Japan
| |
Collapse
|
3
|
Konno H, Yasumiishi H, Aoki R, Nitanai I, Yano S. Detection of Thiol Functionality and Disulfide Bond Formation by Polyoxometalate. ACS COMBINATORIAL SCIENCE 2020; 22:745-749. [PMID: 33030888 DOI: 10.1021/acscombsci.0c00176] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The detection of thiol functionality and intramolecular disulfide bond formation of peptides using the α-Keggin type polyoxometalate molybdenum-oxygen cluster (H3PMo12O40·nH2O) is described. Our method entails the addition of this polyoxometalate to solutions of thiol, whereupon the color of the solution changes from colorless to deep blue. Reduction of the polyoxometalate from Mo(VI) to Mo(V) occurs with concomitant oxidation of the thiol functionality, to form disulfide bonds. To exemplify the utility this phenomenon, we accomplished the oxidation of glutathione, reduced linear oxytocin, bactenecin, and α-conotoxin SI; all of which proceeded smoothly and in good conversion in 24 h to less and were accomplished by a change in the color of the reaction solutions.
Collapse
Affiliation(s)
- Hiroyuki Konno
- Department of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, Yonezawa, Yamagata 992-8510, Japan
| | - Haruto Yasumiishi
- Department of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, Yonezawa, Yamagata 992-8510, Japan
| | - Reika Aoki
- Department of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, Yonezawa, Yamagata 992-8510, Japan
| | - Ikumi Nitanai
- Department of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, Yonezawa, Yamagata 992-8510, Japan
| | - Shigekazu Yano
- Department of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, Yonezawa, Yamagata 992-8510, Japan
| |
Collapse
|
4
|
Zhu A, Wang T, Feng W, Wang J, Li L. Biocompatible ionic liquid [Betaine][H 2PO 4] as a reusable catalyst for the substitution of xanthen-9-ol under solvent-free conditions. RSC Adv 2020; 10:31662-31669. [PMID: 35520689 PMCID: PMC9056413 DOI: 10.1039/d0ra05374k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/08/2020] [Indexed: 11/21/2022] Open
Abstract
An ionic liquid, namely [Betaine][H2PO4], was found to be an efficient catalyst for the direct substitution reaction of xanthen-9-ol with different nucleophiles under solvent-free conditions. This catalytic system is easy to be operated and the following work-up procedure is simple, with the ionic liquid catalyst reusable for at least five cycles at a high catalytic activity level. In addition, the ionic liquid is easy to prepare and its raw materials are inexpensive and have good biocompatibility. Therefore, our study presents an intriguing and sustainable protocol for the direct substitution of alcohol.
Collapse
Affiliation(s)
- Anlian Zhu
- School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Henan Normal University Xinxiang Henan 453007 P. R. China
| | - Tong Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Henan Normal University Xinxiang Henan 453007 P. R. China
| | - Wanlu Feng
- School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Henan Normal University Xinxiang Henan 453007 P. R. China
| | - Jianji Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Henan Normal University Xinxiang Henan 453007 P. R. China
| | - Lingjun Li
- School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Henan Normal University Xinxiang Henan 453007 P. R. China
| |
Collapse
|
5
|
Ste.Marie EJ, Hondal RJ. 2,2'-Dipyridyl diselenide: A chemoselective tool for cysteine deprotection and disulfide bond formation. J Pept Sci 2020; 26:e3236. [PMID: 31856422 PMCID: PMC7509986 DOI: 10.1002/psc.3236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 10/26/2019] [Accepted: 11/04/2019] [Indexed: 11/05/2022]
Abstract
There are many examples of bioactive, disulfide-rich peptides and proteins whose biological activity relies on proper disulfide connectivity. Regioselective disulfide bond formation is a strategy for the synthesis of these bioactive peptides, but many of these methods suffer from a lack of orthogonality between pairs of protected cysteine (Cys) residues, efficiency, and high yields. Here, we show the utilization of 2,2'-dipyridyl diselenide (PySeSePy) as a chemical tool for the removal of Cys-protecting groups and regioselective formation of disulfide bonds in peptides. We found that peptides containing either Cys(Mob) or Cys(Acm) groups treated with PySeSePy in trifluoroacetic acid (TFA) (with or without triisopropylsilane (TIS) were converted to Cys-S-SePy adducts at 37 °C and various incubation times. This novel Cys-S-SePy adduct is able to be chemoselectively reduced by five-fold excess ascorbate at pH 4.5, a condition that should spare already installed peptide disulfide bonds from reduction. This chemoselective reduction by ascorbate will undoubtedly find utility in numerous biotechnological applications. We applied our new chemistry to the iodine-free synthesis of the human intestinal hormone guanylin, which contains two disulfide bonds. While we originally envisioned using ascorbate to chemoselectively reduce one of the formed Cys-S-SePy adducts to catalyze disulfide bond formation, we found that when pairs of Cys(Acm) residues were treated with PySeSePy in TFA, the second disulfide bond formed spontaneously. Spontaneous formation of the second disulfide is most likely driven by the formation of the thermodynamically favored diselenide (PySeSePy) from the two Cys-S-SePy adducts. Thus, we have developed a one-pot method for concomitant deprotection and disulfide bond formation of Cys(Acm) pairs in the presence of an existing disulfide bond.
Collapse
Affiliation(s)
- Emma J. Ste.Marie
- Department of Chemistry, Discovery Hall, University of Vermont, 82 University Place, Burlington, VT 05405, USA
- ESM was supported by National Institutes of Health Training Grant T32 HL07594 administered by Dr. Kenneth G. Mann and Dr. Robert J. Kelm
| | - Robert J. Hondal
- Department of Chemistry, Discovery Hall, University of Vermont, 82 University Place, Burlington, VT 05405, USA
- University of Vermont, Department of Biochemistry, 89 Beaumont Ave, Given Laboratory, Room B413, Burlington, VT 05405, USA
| |
Collapse
|
6
|
Patil NA, Karas JA, Wade JD, Hossain MA, Tailhades J. Rapid Photolysis‐Mediated Folding of Disulfide‐Rich Peptides. Chemistry 2019; 25:8599-8603. [DOI: 10.1002/chem.201901334] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Indexed: 12/11/2022]
Affiliation(s)
- Nitin A. Patil
- The Monash Biomedicine Discovery Institute 15 Innovation Walk Clayton VIC 3800 Australia
| | - John A. Karas
- Department of Pharmacology and TherapeuticsThe University of Melbourne Victoria 3010 Australia
| | - John D. Wade
- Department of Pharmacology and TherapeuticsThe University of Melbourne Victoria 3010 Australia
- The Florey Institute of Neuroscience and Mental HealthUniversity of Melbourne 30 Royal Parade, Parkville Victoria 3052 Australia
| | - Mohammed Akhter Hossain
- Department of Pharmacology and TherapeuticsThe University of Melbourne Victoria 3010 Australia
- The Florey Institute of Neuroscience and Mental HealthUniversity of Melbourne 30 Royal Parade, Parkville Victoria 3052 Australia
| | - Julien Tailhades
- The Monash Biomedicine Discovery Institute 15 Innovation Walk Clayton VIC 3800 Australia
- EMBL AustraliaMonash University Clayton Victoria 3800 Australia
| |
Collapse
|
7
|
Structure and function of μ-conotoxins, peptide-based sodium channel blockers with analgesic activity. Future Med Chem 2015; 6:1677-98. [PMID: 25406007 DOI: 10.4155/fmc.14.107] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
μ-Conotoxins block voltage-gated sodium channels (VGSCs) and compete with tetrodotoxin for binding to the sodium conductance pore. Early efforts identified µ-conotoxins that preferentially blocked the skeletal muscle subtype (NaV1.4). However, the last decade witnessed a significant increase in the number of µ-conotoxins and the range of VGSC subtypes inhibited (NaV1.2, NaV1.3 or NaV1.7). Twenty µ-conotoxin sequences have been identified to date and structure-activity relationship studies of several of these identified key residues responsible for interactions with VGSC subtypes. Efforts to engineer-in subtype specificity are driven by in vivo analgesic and neuromuscular blocking activities. This review summarizes structural and pharmacological studies of µ-conotoxins, which show promise for development of selective blockers of NaV1.2, and perhaps also NaV1.1,1.3 or 1.7.
Collapse
|
8
|
Akondi KB, Muttenthaler M, Dutertre S, Kaas Q, Craik DJ, Lewis RJ, Alewood PF. Discovery, synthesis, and structure-activity relationships of conotoxins. Chem Rev 2014; 114:5815-47. [PMID: 24720541 PMCID: PMC7610532 DOI: 10.1021/cr400401e] [Citation(s) in RCA: 224] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | | | - Sébastien Dutertre
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - Quentin Kaas
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - Richard J Lewis
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - Paul F Alewood
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| |
Collapse
|
9
|
Postma TM, Albericio F. N-Chlorosuccinimide, an efficient reagent for on-resin disulfide formation in solid-phase peptide synthesis. Org Lett 2013; 15:616-9. [PMID: 23320397 DOI: 10.1021/ol303428d] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
N-Chlorosuccinimide is described as a widely applicable on-resin disulfide-forming reagent. Disulfide bond formation was completed within 15 min in DMF. This strategy was successfully used in the synthesis of oxytocin and a regioselective synthesis of an α-conotoxin. Moreover, disulfide formation with N-chlorosuccinimide was found to be compatible with oxidation-prone methionine and tryptophan.
Collapse
Affiliation(s)
- Tobias M Postma
- Institute for Research in Biomedicine, Barcelona 08028, Spain
| | | |
Collapse
|
10
|
Bingham JP, Andrews EA, Kiyabu SM, Cabalteja CC. Drugs from slugs. Part II--conopeptide bioengineering. Chem Biol Interact 2012; 200:92-113. [PMID: 23063744 DOI: 10.1016/j.cbi.2012.09.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Revised: 08/27/2012] [Accepted: 09/17/2012] [Indexed: 11/27/2022]
Abstract
The biological transformation of toxins as research probes, or as pharmaceutical drug leads, is an onerous and drawn out process. Issues regarding changes to pharmacological specificity, desired potency, and bioavailability are compounded naturally by their inherent toxicity. These often scuttle their progress as they move up the narrowing drug development pipeline. Yet one class of peptide toxins, from the genus Conus, has in many ways spearheaded the expansion of new peptide bioengineering techniques to aid peptide toxin pharmaceutical development. What has now emerged is the sequential bioengineering of new research probes and drug leads that owe their lineage to these highly potent and isoform specific peptides. Here we discuss the progressive bioengineering steps that many conopeptides have transitioned through, and specifically illustrate some of the biochemical approaches that have been established to maximize their biological research potential and pharmaceutical worth.
Collapse
Affiliation(s)
- Jon-Paul Bingham
- Department of Molecular Biosciences and Bioengineering, University of Hawaii, Honolulu, HI 96822, USA.
| | | | | | | |
Collapse
|
11
|
Efficient synthesis of novel 9H-xanthen-9-yl derivatives of bidentate heterocyclic nucleophiles by Fe(HSO4)3 as a catalyst. CHINESE CHEM LETT 2012. [DOI: 10.1016/j.cclet.2012.08.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
12
|
Liu LY, Zhang Y, Huang KM, Chang WX, Li J. 1,3-Dichloro-tetra-n-butyl-distannoxane: a new application for catalyzing the direct substitution of 9H-xanthen-9-ol at room temperature. Appl Organomet Chem 2012. [DOI: 10.1002/aoc.1856] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Ling-yan Liu
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry; Nankai University; Tianjin; 300071; People's Republic of China
| | - Yan Zhang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry; Nankai University; Tianjin; 300071; People's Republic of China
| | - Kai-meng Huang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry; Nankai University; Tianjin; 300071; People's Republic of China
| | - Wei-xing Chang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry; Nankai University; Tianjin; 300071; People's Republic of China
| | - Jing Li
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry; Nankai University; Tianjin; 300071; People's Republic of China
| |
Collapse
|
13
|
Liu LY, Wang B, Yang HM, Chang WX, Li J. The direct substitutions of 9H-xanthen-9-ol with indoles in a room temperature ionic liquid medium BmimBF4. Tetrahedron Lett 2011. [DOI: 10.1016/j.tetlet.2011.08.085] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
14
|
Empting M, Avrutina O, Meusinger R, Fabritz S, Reinwarth M, Biesalski M, Voigt S, Buntkowsky G, Kolmar H. "Triazole bridge": disulfide-bond replacement by ruthenium-catalyzed formation of 1,5-disubstituted 1,2,3-triazoles. Angew Chem Int Ed Engl 2011; 50:5207-11. [PMID: 21544910 DOI: 10.1002/anie.201008142] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 02/21/2011] [Indexed: 12/20/2022]
Affiliation(s)
- Martin Empting
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Petersenstrasse 22, 64287 Darmstadt, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Empting M, Avrutina O, Meusinger R, Fabritz S, Reinwarth M, Biesalski M, Voigt S, Buntkowsky G, Kolmar H. “Triazolbrücke”: ein Disulfidbrückenersatz durch Ruthenium- katalysierte Bildung von 1,5-disubstituierten 1,2,3-Triazolen. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201008142] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
|
16
|
Bingham JP, Mitsunaga E, Bergeron ZL. Drugs from slugs--past, present and future perspectives of omega-conotoxin research. Chem Biol Interact 2010; 183:1-18. [PMID: 19800874 DOI: 10.1016/j.cbi.2009.09.021] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 09/03/2009] [Accepted: 09/24/2009] [Indexed: 12/18/2022]
Abstract
Peptides from the venom of carnivorous cone shells have provided six decades of intense research, which has led to the discovery and development of novel analgesic peptide therapeutics. Our understanding of this unique natural marine resource is however somewhat limited. Given the past pharmacological record, future investigations into the toxinology of these highly venomous tropical marine snails will undoubtedly yield other highly selective ion channel inhibitors and modulators. With over a thousand conotoxin-derived sequences identified to date, those identified as ion channel inhibitors represent only a small fraction of the total. Here we discuss our present understanding of conotoxins, focusing on the omega-conotoxin peptide family, and illustrate how such a seemingly simple snail has yielded a highly effective clinical drug.
Collapse
Affiliation(s)
- Jon-Paul Bingham
- Department of Molecular Biosciences and Bioengineering, University of Hawaii, Honolulu, HI 96822, USA.
| | | | | |
Collapse
|
17
|
Da Silva P, Strzepa A, Jouvensal L, Rahioui I, Gressent F, Delmas AF. A folded and functional synthetic PA1b: an interlocked entomotoxic miniprotein. Biopolymers 2009; 92:436-44. [PMID: 19399851 DOI: 10.1002/bip.21217] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
PA1b (Pea Albumin 1, subunit b) is a hydrophobic, 37-amino acid miniprotein isolated from pea seeds (Pivum sativum), crosslinked by three interlocked disulfide bridges, signature of the ICK (inhibitory cystine-knot) family. It acts as an entomotoxic factor against major insect pests in stored crops and vegetables, making it a promising bioinsecticide. Here we report an efficient and simple protocol for the production of large quantities of highly pure, biologically active synthetic PA1b. The features of PA1b oxidative refolding revealed the off-pathway products and competitive aggregation processes. The efficiency of the oxidative folding can be significantly improved by using hydrophobic alcoholic cosolvents and decreasing the temperature. The homogeneity of the synthetic oxidized PA1b was established by reversed-phase HPLC. The correct pairing of the three disulfide bridges, as well as the three-dimensional structure of synthetic PA1b was assessed by NMR. Synthetic PA1b binds to microsomal proteins from Sitophilus oryzae with a Kd of 8 nM, a figure quite similar to that determined for PA1b extracted from its natural source. Moreover, the synthetic miniprotein was as potent as the extracted one towards the sensitive strains of weevils. Our findings will open the way to the production of PA1b analogues by chemical means to an in-depth understanding of the PA1b mechanism of action.
Collapse
Affiliation(s)
- Pedro Da Silva
- Université de Lyon, INRA, INSA-Lyon, IFR-41, UMR203 BF2I, Biologie Fonctionnelle Insectes et Interactions, Villeurbanne, France
| | | | | | | | | | | |
Collapse
|
18
|
Abstract
The formation of disulfide bridges is often a crucial final stage in peptide synthesis. There is compelling evidence that the disulfide pattern can be critical in the folding and structural stabilization of many natural peptide and protein sequences, while the artificial introduction of disulfide bridges into natural or designed peptides may often improve biological activities/specificities and stabilities. This unit provides a highly selective, albeit state-of-the-art, menu of procedures that can be performed to establish intramolecular or intermolecular disulfide bridges in targets of varying complexities.
Collapse
Affiliation(s)
- L Chen
- AxCell Biosciences Corporation, Newtown, Pennsylvania, USA
| | | | | |
Collapse
|
19
|
Wang S, Ji S. Indium Tris(dodecyl Sulfonate) [In(DS)3]–Catalyzed Formation of 3‐(9H‐Xanthen‐9‐yl)‐1H‐indole Derivatives in Water at Room Temperature. SYNTHETIC COMMUN 2008. [DOI: 10.1080/00397910701578172] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Shun‐Yi Wang
- a Key Laboratory of Organic Synthesis of Jiangsu Province , College of Chemistry and Chemical Engineering of Suzhou (Soochow) University , Suzhou, China
| | - Shun‐Jun Ji
- a Key Laboratory of Organic Synthesis of Jiangsu Province , College of Chemistry and Chemical Engineering of Suzhou (Soochow) University , Suzhou, China
| |
Collapse
|
20
|
Szabó I, Schlosser G, Hudecz F, Mezo G. Disulfide bond rearrangement during regioselective oxidation in PhS(O)Ph/CH3SiCl3 mixture for the synthesis of alpha-conotoxin GI. Biopolymers 2007; 88:20-8. [PMID: 17063467 DOI: 10.1002/bip.20616] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Rearrangement of disulfide bonds during the synthesis of alpha-conotoxin GI using PhS(O)Ph/CH(3)SiCl(3) oxidation procedure was observed. We have demonstrated that the protecting scheme (order of acetamidomethyl (Acm) and (t)Bu protecting groups) of the Cys residues as well as the reaction time influenced the ratio of the native and the mispaired compounds, while the temperature of the reaction mixture had no significant effect. However, in all cases the nonnative derivative was produced in high amount. The structure of the isomers was identified by the combination of enzymatic digestion and mass spectrometry measurements. We conclude that the air oxidation followed by the application of Tl(tfa)(3) for the regioselective formation of disulfide bonds leads up to the appropriate compound in the case of the synthesis of alpha-conotoxin GI, while the oxidation procedure using PhS(O)Ph/CH(3)SiCl(3) system resulted in the nonnative disulfide isomer.
Collapse
Affiliation(s)
- Ildikó Szabó
- Research Group of Peptide Chemistry, Hungarian Academy of Sciences, Eötvös L. University, Budapest, Hungary
| | | | | | | |
Collapse
|
21
|
Brust A, Tickle AE. High-throughput synthesis of conopeptides: a safety-catch linker approach enabling disulfide formation in 96-well format. J Pept Sci 2007; 13:133-41. [PMID: 17160973 DOI: 10.1002/psc.825] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Conotoxins exhibit a high degree of selectivity and potency for a range of pharmacologically relevant targets. The rapid access to libraries of conotoxin analogues, containing multiple intramolecular disulfide bridges for use in drug development, can be a very labor intensive, multi-step task. This work describes a high-throughput method for the synthesis of cystine-bridged conopeptides. Peptides were assembled on a peptide synthesizer employing the Fmoc solid-phase strategy using a safety-catch amide linker (SCAL). Side-chain protecting groups were removed on solid phase before SCAL activation with ammonium iodide in TFA, finally releasing the peptide into the TFA solution. Disulfide bond formation was performed in the cleavage mixture employing DMSO. This improved method allows mixtures of oxidized peptides to be obtained in parallel directly from a peptide synthesizer. A single HPLC purification of the resulting crude oxidized material produced peptides of > 95% purity.
Collapse
Affiliation(s)
- Andreas Brust
- Xenome Ltd, 120 Meiers Road, Indooroopilly 4068, Australia.
| | | |
Collapse
|
22
|
Kasheverov IE, Utkin IN, Tsetlin VI. [Natural alpha-conotoxins and their synthetic analogues in studies of nicotinic acetylcholine receptors]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2006; 32:115-29. [PMID: 16637282 DOI: 10.1134/s1068162006020014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
alpha-Conotoxins, peptide neurotoxins from poisonous marine snails of the genus Conus that highly specifically block nicotinic acetylcholine receptors (AChRs) of various types, are reviewed. Preliminarily, the structural organization of AChRs of the muscular and neuronal types, their involvement in physiological processes, and their role in various diseases are briefly discussed. In this connection, the necessity of quantitative determination of AChR subtypes using neurotoxins and other approaches is substantiated. The chemical structure, spatial organization, and specificity of alpha-conotoxins are mainly discussed, taking into consideration the recent results on the ability of alpha-conotoxins to interact with muscular or neuronal hetero- and homooligomeric AChRs exhibiting a high species specificity. Particular emphasis is placed upon a thorough characterization of the surfaces of interaction of alpha-conotoxins with AChRs using synthetic analogues of alpha-conotoxins, mutations in AChRs, and pairwise mutations in both alpha-conotoxins and AChRs. The discovery in 2001 of the acetylcholine-binding protein from the pond snail Lymnaea stagnalis and the determination of its crystalline structure led to rapid progress in understanding the structural organization of ligand-binding domains of AChRs with which alpha-conotoxins also interact. We discuss the interaction of various alpha-conotoxins with acetylcholine-binding proteins, the recently reported X-ray structure of the complex of the acetylcholine-binding protein from Aplysia californica with the alpha-conotoxin analogue PnIA, and the application of this structure to the modeling of complexes of alpha-conotoxins with various AChRs.
Collapse
|
23
|
Joseph CG, Wang XS, Scott JW, Bauzo RM, Xiang Z, Richards NG, Haskell-Luevano C. Stereochemical studies of the monocyclic agouti-related protein (103-122) Arg-Phe-Phe residues: conversion of a melanocortin-4 receptor antagonist into an agonist and results in the discovery of a potent and selective melanocortin-1 agonist. J Med Chem 2005; 47:6702-10. [PMID: 15615519 DOI: 10.1021/jm0492756] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The agouti-related protein (AGRP) is an endogenous antagonist of the centrally expressed melanocortin receptors. The melanocortin-4 receptor (MC4R) is involved in energy homeostasis, food intake, sexual function, and obesity. The endogenous hAGRP protein is 132 amino acids in length, possesses five disulfide bridges at the C-terminus of the molecule, and is expressed in the hypothalamus of the brain. We have previously reported that a monocyclic hAGRP(103-122) peptide is an antagonist at the melanocortin receptors expressed in the brain. Stereochemical inversion from the endogenous l- to d-isomers of single or multiple amino acid modifications in this monocyclic truncated hAGRP sequence resulted in molecules that are converted from melanocortin receptor antagonists into melanocortin receptor agonists. The Asp-Pro-Ala-Ala-Thr-Ala-Tyr-cyclo[Cys-Arg-DPhe-DPhe-Asn-Ala-Phe-Cys]-Tyr-Ala-Arg-Lys-Leu peptide resulted in a 60 nM melanocortin-1 receptor agonist that is 100-fold selective versus the mMC4R, 1000-fold selective versus the mMC3R, and ca. 180-fold selective versus the mMC5R. In attempts to identify putative ligand-receptor interactions that may be participating in the agonist induced stimulation of the MC4R, selected ligands were docked into a homology molecular model of the mMC4R. These modeling studies have putatively identified hAGRP ligand DArg111-mMC4RAsn115 (TM3) and the hAGRP DPhe113-mMC4RPhe176 (TM4) interactions as important for agonist activity.
Collapse
Affiliation(s)
- Christine G Joseph
- Department of Medicinal Chemistry, University of Florida, Gainesville, FL 32610, USA
| | | | | | | | | | | | | |
Collapse
|
24
|
Loughnan ML, Alewood PF. Physico-chemical characterization and synthesis of neuronally active alpha-conotoxins. ACTA ACUST UNITED AC 2004; 271:2294-304. [PMID: 15182345 DOI: 10.1111/j.1432-1033.2004.04146.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The high specificity of alpha-conotoxins for different neuronal nicotinic acetylcholine receptors makes them important probes for dissecting receptor subtype selectivity. New sequences continue to expand the diversity and utility of the pool of available alpha-conotoxins. Their identification and characterization depend on a suite of techniques with increasing emphasis on mass spectrometry and microscale chromatography, which have benefited from recent advances in resolution and capability. Rigorous physico-chemical analysis together with synthetic peptide chemistry is a prerequisite for detailed conformational analysis and to provide sufficient quantities of alpha-conotoxins for activity assessment and structure-activity relationship studies.
Collapse
Affiliation(s)
- Marion L Loughnan
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | | |
Collapse
|
25
|
Joseph CG, Bauzo RM, Xiang Z, Shaw AM, Millard WJ, Haskell-Luevano C. Elongation studies of the human agouti-related protein (AGRP) core decapeptide (Yc[CRFFNAFC]Y) results in antagonism at the mouse melanocortin-3 receptor. Peptides 2003; 24:263-70. [PMID: 12668211 DOI: 10.1016/s0196-9781(03)00030-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The agouti-related protein (AGRP) is an endogenous antagonist of the brain melanocortin receptors (MC3R and MC4R) and is believed to be involved in feeding behavior and energy homeostasis. Previous results identified that the human AGRP decapeptide Yc[CRFFNAFC]Y binds to the MC3R and MC4R and acts as an antagonist at the MC4R but not at the MC3R. We have synthesized the amidated version of this decapeptide as well as performed elongation studies at both the N-and C-terminus of the monocyclic hAGRP(109-118) peptide. This study was designed to identify monocyclic peptide fragments of the hAGRP(86-132) to determine the minimal active monocyclic sequence necessary for antagonism at the MC3R. For binding studies, radiolabeled 125I-NDP-MSH versus 125I-hAGRP(86-132) were utilized to determine if there were differences in the ability of the AGRP fragments prepared herein to competitively displace the 125I-NDP-MSH versus AGRP(86-132) radiolabel. The binding IC(50) values of radiolabeled hAGRP(86-132) versus NDP-MSH were identical within experimental error, supporting the hypothesis that AGRP and NDP-MSH interact with overlapping binding epitopes at the MC3R and MC4R. The most notable results include identification of the TAYc[CRFFNAFC]YAR-NH(2) (pA(2)=6.1, K(i)=790nM, mMC3R) and the Yc[CRFFNAFC]YARKL-NH(2) (pA(2)=6.2, K(i)=630nM, mMC3R) peptides as the minimal monocyclic AGRP-based fragments possessing antagonist pharmacology at the MC3R. Interestingly, extension of the AGRP(109-118) decapeptide at both the N- and C-terminus by two amino acids conferred detectable mMC3R antagonism, while retaining high nanomolar MC4R antagonist and micromolar MC1R agonist pharmacological properties. These data support the hypothesis that elongation of the hAGRP(109-118) decapeptide results in antagonism at the MC3R while retaining MC1R agonist activity and MC4R antagonist activity.
Collapse
Affiliation(s)
- Christine G Joseph
- Department of Medicinal Chemistry, University of Florida, FL 32610, Gainesville, USA. carrie.cop.ufl.edu
| | | | | | | | | | | |
Collapse
|
26
|
Mirgorodskaya OA, Haselmann KF, Kjeldsen F, Zubarev RA, Roepstorff P. Towards the standard-module approach to disulfide-linked polypeptide nanostructures. I. Methodological prerequisites and mass spectrometric characterization of the test two-loop structure. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2003; 9:139-148. [PMID: 12748397 DOI: 10.1255/ejms.539] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Potentially biologically-active nanostructures can be created from single chains of unmodified peptides by cross-linking different regions of the chain by disulfide bonds and cleaving the chain at specified sites to obtain the final configuration. The availability of techniques for assembly and characterization of such structures was tested on a two-loop structure created from a 21-residue linear peptide. Directed intra-molecular disulfide bond formation was performed by inserting partial sequences favoring intra-molecular SS bond formation ("loops") separated by partial sequences disfavoring such a process ("spacers") into the precursor sequence. Peptide bond cleavage by partial acid hydrolysis at specific sites (GG, NP/DP) inside the loops opened them; the same process in the spacer separated the loops. Synthesis, oxidation and bond cleavage were monitored by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI ToF MS). The hydrolysis fragments of the produced nanostructures were characterized by tandem electrospray ionization Fourier transform mass spectrometry (ESI FT-MS) with collisional and electron capture dissociations. The latter technique was especially useful as it cleaves SS bonds preferentially. The feasibility of the proposed synthesis approach and the adequacy of the analysis techniques for the test structure were demonstrated.
Collapse
Affiliation(s)
- O A Mirgorodskaya
- Department of Chemistry, University of Southern Denmark, Odense, Denmark
| | | | | | | | | |
Collapse
|
27
|
|
28
|
Shi T, Rabenstein DL. Formation of multiple intramolecular disulfide bonds in peptides using the reagent trans -[Pt(ethylenediamine) 2 Cl 2 ] 2+. Tetrahedron Lett 2001. [DOI: 10.1016/s0040-4039(01)01523-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
29
|
Hargittai B, Solé NA, Groebe DR, Abramson SN, Barany G. Chemical syntheses and biological activities of lactam analogues of alpha-conotoxin SI. J Med Chem 2000; 43:4787-92. [PMID: 11123987 DOI: 10.1021/jm990635c] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bicyclization represents an effective method for the introduction of conformational constraints into small, biologically important peptides. Several strategies have been developed for the preparation of bicyclic lactam analogues of alpha-conotoxin SI, a 13-residue peptide neurotoxin found in cone snail venom. Four analogues of the natural regioisomer of alpha-conotoxin SI were designed and synthesized, each with one of the two paired cysteines of the parent peptide being replaced by a side-chain lactam bridged glutamic acid/lysine pair. Solid-phase lactamization was studied to determine rates of formation of the two possible loops and to document the extent of dimerization and higher oligomerization. Radioligand binding assays were carried out on all synthesized peptides, including the naturally occurring two-disulfide form, in order to determine their affinities for nicotinic acetylcholine receptors (nAChRs). Replacement of the Cys(2)-Cys(7) loop of alpha-conotoxin SI with a lactam bridge resulted in complete loss of activity, whereas replacement of the Cys(3)-Cys(13) disulfide loop resulted in a approximately 60-fold reduction in affinity for one orientation and a approximately 70-fold increase in affinity for the other. The two active lactam analogues retain the selectivity exhibited by the naturally occurring peptide for the alpha/delta subunit of nAChRs, as judged by competition experiments with the curariform antagonist metocurine.
Collapse
Affiliation(s)
- B Hargittai
- Departments of Chemistry and Laboratory Medicine & Pathology, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | | | | | | | | |
Collapse
|
30
|
Abstract
The nuclear magnetic resonance solution structure of alpha-conotoxin SI has been determined at pH 4.2. The 36 lowest energy structures show that alpha-conotoxin SI exists in a single major solution conformation and is stabilized by six hydrogen bonds. Comparisons are made between the SI solution structure and the solution and crystal structures of alpha-conotoxin GI. Surprisingly, a high degree of similarity between the backbone conformations of the GI crystal and the SI solution structures is seen in the region of lowest sequence homology, namely residues Gly-8 to Ser-12. This similarity is more surprising when considering that in SI a proline replaces the Arg-9 found in GI. The correspondence in conformation in this region provides the definitive evidence that it is the loss of the arginine basic charge at residue 9 which determines the differences in toxicity between GI and SI, rather than any changes in conformation induced by the cyclic proline residue.
Collapse
Affiliation(s)
- A J Benie
- Molecular and Cellular Biology, St. Bartholomew's and the Royal London School of Medicine and Dentistry, University of London, UK
| | | | | | | | | |
Collapse
|
31
|
Cuthbertson A, Indrevoll B. A method for the one-pot regioselective formation of the two disulfide bonds of α-conotoxin SI. Tetrahedron Lett 2000. [DOI: 10.1016/s0040-4039(00)00437-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
32
|
Hargittai B, Annis I, Barany G. Application of solid-phase Ellman's reagent for preparation of disulfide-paired isomers of α-conotoxin SI. ACTA ACUST UNITED AC 2000. [DOI: 10.1007/bf02443562] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
33
|
Chen L, Golser R, Machová A, Slaninová J, Barany G. Chemical syntheses and biological studies on dimeric chimeras of oxytocin and the V(2)-antagonist, d(CH(2))(5)[D-Ile(2), Ile(4)]arginine vasopressin. J Med Chem 1999; 42:5002-9. [PMID: 10585209 DOI: 10.1021/jm9900220] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Parallel and antiparallel heterodimers have been synthesized that combine into a single molecule the neurohypophyseal hormone oxytocin and the potent vasopressin V(2)-antagonist d(CH(2))(5)[D-Ile(2), Ile(4)]arginine vasopressin. Solid-phase synthesis with N(alpha)-9-fluorenylmethyloxycarbonyl (Fmoc) chemistry, featuring appropriate combinations of orthogonal protecting groups for the thiols [S-(N-methyl-N-phenylcarbamoyl)sulfenyl (Snm); S-acetamidomethyl (Acm); S-triphenylmethyl (Trt)], was used to assemble the required linear nonapeptide amide monomer intermediates, which were then brought together in defined ways by solution reactions to provide the two heterodimers. The first disulfide bridge was formed by a directed approach involving attack by the free thiol of the 1-beta-mercapto-beta, beta-cyclopentamethylenepropionic acid (Pmp) residue of one monomer onto the Snm group of a cysteine residue on the other monomer; the inverse directed strategy failed due to steric hindrance. The second disulfide bridge was formed by iodine co-oxidation of Cys(Acm) residues on adjacent chains. Biological studies revealed that both the parallel and antiparallel chimeras lack pressor activity, have low uterotonic activity, and have diuretic activities comparable to that of the monomeric V(2)-antagonist. Sodium excretion depends on experimental conditions. Thus, with a 4% water load, both chimeras display effects similar to that of an equimolar mixture of oxytocin and V(2)-antagonist, i.e., lower sodium excretion than that resulting from administration of oxytocin alone but higher than that when V(2)-antagonist was administered alone. However, when no water load was used, the parallel chimera proved to be more effective in promoting sodium excretion than either oxytocin alone or an equimolar mixture of oxytocin and V(2)-antagonist.
Collapse
Affiliation(s)
- L Chen
- Departments of Chemistry and Laboratory Medicine & Pathology, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | | | | | | | | |
Collapse
|