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Lund PM, Kristensen K, Larsen NW, Knuhtsen A, Hansen MB, Hjørringgaard CU, Eriksen AZ, Urquhart AJ, Mortensen KI, Simonsen JB, Andresen TL, Larsen JB. Tuning the double lipidation of salmon calcitonin to introduce a pore-like membrane translocation mechanism. J Colloid Interface Sci 2024; 669:198-210. [PMID: 38713958 DOI: 10.1016/j.jcis.2024.04.093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 04/10/2024] [Accepted: 04/14/2024] [Indexed: 05/09/2024]
Abstract
A widespread strategy to increase the transport of therapeutic peptides across cellular membranes has been to attach lipid moieties to the peptide backbone (lipidation) to enhance their intrinsic membrane interaction. Efforts in vitro and in vivo investigating the correlation between lipidation characteristics and peptide membrane translocation efficiency have traditionally relied on end-point read-out assays and trial-and-error-based optimization strategies. Consequently, the molecular details of how therapeutic peptide lipidation affects it's membrane permeation and translocation mechanisms remain unresolved. Here we employed salmon calcitonin as a model therapeutic peptide and synthesized nine double lipidated analogs with varying lipid chain lengths. We used single giant unilamellar vesicle (GUV) calcein influx time-lapse fluorescence microscopy to determine how tuning the lipidation length can lead to an All-or-None GUV filling mechanism, indicative of a peptide mediated pore formation. Finally, we used a GUVs-containing-inner-GUVs assay to demonstrate that only peptide analogs capable of inducing pore formation show efficient membrane translocation. Our data provided the first mechanistic details on how therapeutic peptide lipidation affects their membrane perturbation mechanism and demonstrated that fine-tuning lipidation parameters could induce an intrinsic pore-forming capability. These insights and the microscopy based workflow introduced for investigating structure-function relations could be pivotal for optimizing future peptide design strategies.
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Affiliation(s)
- Philip M Lund
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, Lyngby, Denmark; DTU Health Tech, Department of Health Technology, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Kasper Kristensen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, Lyngby, Denmark; DTU Health Tech, Department of Health Technology, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Nanna W Larsen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, Lyngby, Denmark; DTU Health Tech, Department of Health Technology, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Astrid Knuhtsen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, Lyngby, Denmark; DTU Health Tech, Department of Health Technology, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Morten B Hansen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, Lyngby, Denmark; DTU Health Tech, Department of Health Technology, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Claudia U Hjørringgaard
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, Lyngby, Denmark; DTU Health Tech, Department of Health Technology, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Anne Z Eriksen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, Lyngby, Denmark; DTU Health Tech, Department of Health Technology, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Andrew J Urquhart
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, Lyngby, Denmark; DTU Health Tech, Department of Health Technology, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Kim I Mortensen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, Lyngby, Denmark; DTU Health Tech, Department of Health Technology, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Jens B Simonsen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, Lyngby, Denmark; DTU Health Tech, Department of Health Technology, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Thomas L Andresen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, Lyngby, Denmark; DTU Health Tech, Department of Health Technology, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
| | - Jannik B Larsen
- Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, Lyngby, Denmark; DTU Health Tech, Department of Health Technology, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
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2
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Chen K, Smith CJ. Best Practices for Submission of NMR Data to Support Higher Order Structure Assessment of Generic Peptide Drugs. AAPS J 2023; 25:17. [PMID: 36670271 DOI: 10.1208/s12248-023-00782-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 01/05/2023] [Indexed: 01/22/2023] Open
Affiliation(s)
- Kang Chen
- Division of Complex Drug Analysis, Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, 20993, USA.
| | - Cameron J Smith
- Division of Liquid-Based Products I, Office of Lifecycle Drug Products, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, 20993, USA
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3
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Liu Y, Wang Y, Zhang Y, Zou Y, Wei G, Ding F, Sun Y. Structural Perturbation of Monomers Determines the Amyloid Aggregation Propensity of Calcitonin Variants. J Chem Inf Model 2023; 63:308-320. [PMID: 36456917 PMCID: PMC9839651 DOI: 10.1021/acs.jcim.2c01202] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Human calcitonin (hCT) is a polypeptide hormone that participates in calcium-phosphorus metabolism. Irreversible aggregation of 32-amino acid hCT into β-sheet-rich amyloid fibrils impairs physiological activity and increases the risk of medullary carcinoma of the thyroid. Amyloid-resistant hCT derivatives substituting critical amyloidogenic residues are of particular interest for clinical applications as therapeutic drugs against bone-related diseases. Uncovering the aggregation mechanism of hCT at the molecular level, therefore, is important for the design of amyloid-resistant hCT analogues. Here, we investigated the aggregation dynamics of hCT, non-amyloidogenic salmon calcitonin (sCT), and two hCT analogues with reduced aggregation tendency─TL-hCT and phCT─using long timescale discrete molecular dynamics simulations. Our results showed that hCT monomers mainly adopted unstructured conformations with dynamically formed helices around the central region. hCT self-assembled into helix-rich oligomers first, followed by a conformational conversion into β-sheet-rich oligomers with β-sheets formed by residues 10-30 and stabilized by aromatic and hydrophobic interactions. Our simulations confirmed that TL-hCT and phCT oligomers featured more helices and fewer β-sheets than hCT. Substitution of central aromatic residues with leucine in TL-hCT and replacing C-terminal hydrophobic residue with hydrophilic amino acid in phCT only locally suppressed β-sheet propensities in the central region and C-terminus, respectively. Having mutations in both central and C-terminal regions, sCT monomers and dynamically formed oligomers predominantly adopted helices, confirming that both central aromatic and C-terminal hydrophobic residues played important roles in the fibrillization of hCT. We also observed the formation of β-barrel intermediates, postulated as the toxic oligomers in amyloidosis, for hCT but not for sCT. Our computational study depicts a complete picture of the aggregation dynamics of hCT and the effects of mutations. The design of next-generation amyloid-resistant hCT analogues should consider the impact on both amyloidogenic regions and also take into account the amplification of transient β-sheet population in monomers upon aggregation.
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Affiliation(s)
- Yuying Liu
- Department of Physics, Ningbo University, Ningbo 315211, China
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, P. R. China
| | - Ying Wang
- Department of Physics, Ningbo University, Ningbo 315211, China
| | - Yu Zhang
- Department of Physics, Ningbo University, Ningbo 315211, China
| | - Yu Zou
- Department of Sport and Exercise Science, Zhejiang University, Hangzhou 310058, China
| | - Guanghong Wei
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, P. R. China
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
| | - Yunxiang Sun
- Department of Physics, Ningbo University, Ningbo 315211, China
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, P. R. China
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
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Paul S, Paul S. Controlling the self-assembly of human calcitonin: a theoretical approach using molecular dynamics simulations. Phys Chem Chem Phys 2021; 23:14496-14510. [PMID: 34184696 DOI: 10.1039/d1cp00825k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Human calcitonin (hCT) is a 32-residue amino acid poly-peptide hormone which is secreted by the C-cells (also known as parafollicular cells) of thyroid glands. It acts to inhibit osteoclast cell hormones by reducing the cell function and regulating calcium and phosphate in blood. hCT has a high tendency to assemble into protofilaments with β-sheet conformations. Amyloid fibril formation of hCT reduces its bio-activity and limits its application as a therapeutic drug. Salmon calcitonin (sCT), which also carries the same disulfide bridge at the N and C-terminus, but differs at the 16 residue position from hCT, has less propensity to aggregate than hCT. Human calcitonin has much higher bio-activity than sCT if its aggregation propensity is reduced. Substituting the key residues which are responsible for the aggregation of hCT, is one of the ways to reduce its aggregation and fibril formation. hCT analogues with less aggregation tendency can be exploited as therapeutic drugs. In this work, we study the amyloidogenic behavior of hCT and its peptide based derivatives i.e., sCT, phCT, N17H hCT, Y12L hCT and DM hCT, through classical molecular dynamics (MD) simulations. Our study reveals that sCT is the least aggregation prone derivative, and the double mutation at position 12 and 17 can reduce the aggregation propensity of this peptide. Also, we have applied these mutant variants of hCT as peptide inhibitors in the self-aggregation of hCT. This study could help in understanding and preparing peptide-based inhibitors for hCT fibrillation and their applications as therapeutic drugs.
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Affiliation(s)
- Srijita Paul
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India.
| | - Sandip Paul
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India.
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Venko K, Novič M, Stoka V, Žerovnik E. Prediction of Transmembrane Regions, Cholesterol, and Ganglioside Binding Sites in Amyloid-Forming Proteins Indicate Potential for Amyloid Pore Formation. Front Mol Neurosci 2021; 14:619496. [PMID: 33642992 PMCID: PMC7902868 DOI: 10.3389/fnmol.2021.619496] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 01/12/2021] [Indexed: 12/26/2022] Open
Abstract
Besides amyloid fibrils, amyloid pores (APs) represent another mechanism of amyloid induced toxicity. Since hypothesis put forward by Arispe and collegues in 1993 that amyloid-beta makes ion-conducting channels and that Alzheimer's disease may be due to the toxic effect of these channels, many studies have confirmed that APs are formed by prefibrillar oligomers of amyloidogenic proteins and are a common source of cytotoxicity. The mechanism of pore formation is still not well-understood and the structure and imaging of APs in living cells remains an open issue. To get closer to understand AP formation we used predictive methods to assess the propensity of a set of 30 amyloid-forming proteins (AFPs) to form transmembrane channels. A range of amino-acid sequence tools were applied to predict AP domains of AFPs, and provided context on future experiments that are needed in order to contribute toward a deeper understanding of amyloid toxicity. In a set of 30 AFPs we predicted their amyloidogenic propensity, presence of transmembrane (TM) regions, and cholesterol (CBM) and ganglioside binding motifs (GBM), to which the oligomers likely bind. Noteworthy, all pathological AFPs share the presence of TM, CBM, and GBM regions, whereas the functional amyloids seem to show just one of these regions. For comparative purposes, we also analyzed a few examples of amyloid proteins that behave as biologically non-relevant AFPs. Based on the known experimental data on the β-amyloid and α-synuclein pore formation, we suggest that many AFPs have the potential for pore formation. Oligomerization and α-TM helix to β-TM strands transition on lipid rafts seem to be the common key events.
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Affiliation(s)
- Katja Venko
- Theory Department, National Institute of Chemistry, Ljubljana, Slovenia
| | - Marjana Novič
- Theory Department, National Institute of Chemistry, Ljubljana, Slovenia
| | - Veronika Stoka
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Eva Žerovnik
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
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6
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Alıcı H, Demir K. Investigation of the stability and the helix-tail interaction of sCT and its various charged mutants based on comparative molecular dynamics simulations. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2020.111057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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7
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Investigation of the effect of transition metals (MN, CO, GD) on the spatial structure of fibrinopeptide B by NMR spectroscopy. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2019.127484] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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8
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Chen YT, Hu KW, Huang BJ, Lai CH, Tu LH. Inhibiting Human Calcitonin Fibril Formation with Its Most Relevant Aggregation-Resistant Analog. J Phys Chem B 2019; 123:10171-10180. [PMID: 31692350 DOI: 10.1021/acs.jpcb.9b08514] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The most common obstacles to the development of therapeutic polypeptides are peptide stability and aggregation. Human calcitonin (hCT) is a 32-residue hormone polypeptide secreted from the C-cells of the thyroid gland and is responsible for calcium and phosphate regulation in the blood. hCT reduces calcium levels by inhibiting the activity of osteoclasts, which are bone cells that are mainly responsible for breaking down the bone tissue or decreasing the resorption of calcium from the kidneys. Thus, calcitonin injection has been used to treat osteoporosis and Paget's disease of bone. hCT is an aggregation-prone peptide with a high tendency to form amyloid fibrils. As a result, salmon calcitonin (sCT), which is different from hCT at 16-residue positions and has a lower propensity to aggregate, has been chosen as a clinical substitute for hCT. However, significant side effects, including immune reactions, have been shown with the use of sCT injection. In this study, we found that two residues, Tyr-12 and Asn-17, play key roles in inducing the fibrillization of hCT. Double mutation of hCT at these two crucial sites could greatly enhance its resistance to aggregation and provide a peptide-based inhibitor to prevent amyloid formation by hCT. Double-mutated hCT retains its ability to interact with its receptor in vivo. These findings suggest that this variant of hCT would serve as a valuable therapeutic alternative to sCT.
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Affiliation(s)
- Yi-Ting Chen
- Department of Chemistry , National Taiwan Normal University , Taipei 116 , Taiwan
| | - Kai-Wei Hu
- Department of Chemistry , National Taiwan Normal University , Taipei 116 , Taiwan
| | - Bo-Jie Huang
- Graduate Institute of Biomedical Engineering , National Chung Hsing University , Taichung 402 , Taiwan
| | - Chian-Hui Lai
- Graduate Institute of Biomedical Engineering , National Chung Hsing University , Taichung 402 , Taiwan
| | - Ling-Hsien Tu
- Department of Chemistry , National Taiwan Normal University , Taipei 116 , Taiwan
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9
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Sekiguchi T, Shiraishi A, Satake H, Kuwasako K, Takahashi H, Sato M, Urata M, Wada S, Endo M, Ikari T, Hattori A, Srivastav AK, Suzuki N. Calcitonin-typical suppression of osteoclastic activity by amphioxus calcitonin superfamily peptides and insights into the evolutionary conservation and diversity of their structures. Gen Comp Endocrinol 2017; 246:294-300. [PMID: 28062302 DOI: 10.1016/j.ygcen.2017.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 12/05/2016] [Accepted: 01/02/2017] [Indexed: 01/27/2023]
Abstract
Calcitonin (CT) is a hormone that decreases serum calcium level by suppressing osteoclastic activity in the vertebrate bone. In vertebrates, the structure-function relationship of CTs has been studied extensively. We recently identified three CT superfamily peptides, Bf-CTFP1 to 3, and clarified the molecular and functional characteristics of their receptor and receptor activity-modifying protein in amphioxus, Branchiostoma floridae. However, the CT activity of Bf-CTFPs has yet to be investigated. In the present study, a functional analysis of Bf-CTFPs was performed using goldfish scales having both osteoclasts and osteoblasts. All Bf-CTFPs suppressed osteoclastic activity via a goldfish CT receptor. Although the primary amino acid sequences of the Bf-CTFPs showed low sequence similarity to vertebrate CTs, Bf-CTFP1 to 3 share three amino acids, Thr25, Thr27, and Pro32-NH2, that are required for receptor binding, with salmon CT. Moreover, homology model analysis revealed that the Bf-CTFPs form alpha-helical structures. The alpha-helical position and length of Bf-CTFP1 and 2 were conserved with those of a highly potent ligand, teleost CT. Interestingly, the composition of the alpha-helix of Bf-CTFP3 differed from those of teleost CT, despite that the action of Bf-CTFP3 on goldfish scales was the same as that of Bf-CTFP1 and 2. Collectively, the present study provides new insights into the structure-function relationship of CT and its functional evolution in chordates.
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Affiliation(s)
- Toshio Sekiguchi
- Noto Marine Laboratory, Institute of Nature and Environmental Technology, Division of Marine Environmental Studies, Kanazawa University, Housu-gun, Ishikawa 927-0553, Japan
| | - Akira Shiraishi
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1, Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
| | - Honoo Satake
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1, Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan
| | - Kenji Kuwasako
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Miyazaki 889-1692, Japan
| | - Hiroki Takahashi
- National Institute for Basic Biology, Laboratory of Morphogenesis, 38 Nishigonaka Myodaiji, Okazaki 444-8585, Japan
| | - Masayuki Sato
- Noto Marine Laboratory, Institute of Nature and Environmental Technology, Division of Marine Environmental Studies, Kanazawa University, Housu-gun, Ishikawa 927-0553, Japan
| | - Makoto Urata
- Noto Marine Laboratory, Institute of Nature and Environmental Technology, Division of Marine Environmental Studies, Kanazawa University, Housu-gun, Ishikawa 927-0553, Japan; Institute of Noto SATOUMI Education and Studies, Noto-cho, Ishikawa 927-0553, Japan
| | - Shuichi Wada
- Department of Animal Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, Nagahama, Shiga 526-0829, Japan
| | - Masato Endo
- Department of Marine Biosciences, Division of Marine Science, Tokyo University of Marine Science and Technology, Minato-ku, Tokyo 108-8477, Japan
| | - Takahiro Ikari
- Noto Marine Laboratory, Institute of Nature and Environmental Technology, Division of Marine Environmental Studies, Kanazawa University, Housu-gun, Ishikawa 927-0553, Japan
| | - Atsuhiko Hattori
- Department of Biology, College of Liberal Arts and Sciences, Tokyo Medical and Dental University, Ichikawa, Chiba 272-0827, Japan
| | - Ajai K Srivastav
- Department of Zoology, D.D.U. Gorakhpur University, Gorakhpur 273-009, India
| | - Nobuo Suzuki
- Noto Marine Laboratory, Institute of Nature and Environmental Technology, Division of Marine Environmental Studies, Kanazawa University, Housu-gun, Ishikawa 927-0553, Japan.
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Johansson E, Hansen JL, Hansen AMK, Shaw AC, Becker P, Schäffer L, Reedtz-Runge S. Type II Turn of Receptor-bound Salmon Calcitonin Revealed by X-ray Crystallography. J Biol Chem 2016; 291:13689-98. [PMID: 27189946 DOI: 10.1074/jbc.m116.726034] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Indexed: 12/20/2022] Open
Abstract
Calcitonin is a peptide hormone consisting of 32 amino acid residues and the calcitonin receptor is a Class B G protein-coupled receptor (GPCR). The crystal structure of the human calcitonin receptor ectodomain (CTR ECD) in complex with a truncated analogue of salmon calcitonin ([BrPhe(22)]sCT(8-32)) has been determined to 2.1-Å resolution. Parallel analysis of a series of peptide ligands showed that the rank order of binding of the CTR ECD is identical to the rank order of binding of the full-length CTR, confirming the structural integrity and relevance of the isolated CTR ECD. The structure of the CTR ECD is similar to other Class B GPCRs and the ligand binding site is similar to the binding site of the homologous receptors for the calcitonin gene-related peptide (CGRP) and adrenomedulin (AM) recently published (Booe, J. M., Walker, C. S., Barwell, J., Kuteyi, G., Simms, J., Jamaluddin, M. A., Warner, M. L., Bill, R. M., Harris, P. W., Brimble, M. A., Poyner, D. R., Hay, D. L., and Pioszak, A. A. (2015) Mol. Cell 58, 1040-1052). Interestingly the receptor-bound structure of the ligand [BrPhe(22)]sCT(8-32) differs from the receptor-bound structure of the homologous ligands CGRP and AM. They all adopt an extended conformation followed by a C-terminal β turn, however, [BrPhe(22)]sCT(8-32) adopts a type II turn (Gly(28)-Thr(31)), whereas CGRP and AM adopt type I turns. Our results suggest that a type II turn is the preferred conformation of calcitonin, whereas a type I turn is the preferred conformation of peptides that require RAMPs; CGRP, AM, and amylin. In addition the structure provides a detailed molecular explanation and hypothesis regarding ligand binding properties of CTR and the amylin receptors.
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Affiliation(s)
- Eva Johansson
- From Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Måløv, Denmark
| | | | | | | | - Peter Becker
- From Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Måløv, Denmark
| | - Lauge Schäffer
- From Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Måløv, Denmark
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Blokhin DS, Fayzullina AR, Filippov AV, Karataeva FK, Klochkov VV. Spatial structure of fibrinopeptide B in water solution with DPC micelles by NMR spectroscopy. J Mol Struct 2015. [DOI: 10.1016/j.molstruc.2015.08.059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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12
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Effect of calcium ions on human calcitonin. Possible implications for bone resorption by osteoclasts. Biometals 2015; 29:61-79. [DOI: 10.1007/s10534-015-9896-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 11/14/2015] [Indexed: 10/22/2022]
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13
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Spatial structure of oligopeptide PAP(248-261), the N-terminal fragment of the HIV enhancer prostatic acid phosphatase peptide PAP(248-286), in aqueous and SDS micelle solutions. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.04.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Itoh-Watanabe H, Kamihira-Ishijima M, Kawamura I, Kondoh M, Nakakoshi M, Sato M, Naito A. Characterization of the spherical intermediates and fibril formation of hCT in HEPES solution using solid-state 13C-NMR and transmission electron microscopy. Phys Chem Chem Phys 2013; 15:16956-64. [PMID: 24002168 DOI: 10.1039/c3cp52810c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Human calcitonin (hCT) is a 32-amino acid peptide hormone that contains an intrachain disulfide bridge between Cys1 and Cys7 and a proline amide at the C-terminus. hCT tends to associate to form a fibril precipitate of the same type as amyloid fibrils, and hence has been studied as a model of amyloid fibril formation. The fibrillation process in N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid (HEPES) solution was examined using transmission electron microscopy. The rate of hCT fibrillation in HEPES solution was much lower than in phosphate buffer and acetic acid solution. Spherical intermediate aggregates (nuclei) were observed during the early stage of fibril formation. Short proto-fibrils appeared on the surface of the spherical intermediates. Subsequently, the spherical intermediates transformed directly into long proto-fibrils, which then elongated into mature hCT fibrils. The fibrillation process was also examined using solid-state (13)C-NMR spectroscopy, which indicated that the fibril structure was a β-sheet in the central region and a mixture of random coils and β-sheets at the C-terminus. The kinetics of fibril formation was examined in terms of a two-step autocatalytic reaction mechanism. The first-step nucleation rate (k1) was lower in HEPES solution than in phosphate buffer and acetic acid solution because the half-life of the intermediates is significantly longer in HEPES solution. In contrast, the second-step fibril elongation rate (k2) was similar in HEPES solution and acidic solutions. Specific interaction of HEPES molecules with hCT may stabilize the spherical intermediates and consequently inhibit the fibril elongation process of hCT.
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Affiliation(s)
- Hikari Itoh-Watanabe
- Graduate School of Engineering, Yokohama National University, Tokiwadai 79-5, Hodogaya-ku, Yokohama 240-8501, Japan.
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15
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Spatial structure of heptapeptide Glu-Ile-Leu-Asn-His-Met-Lys, a fragment of the HIV enhancer prostatic acid phosphatase, in aqueous and SDS micelle solutions. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2012.08.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Itoh-Watanabe H, Kamihira-Ishijima M, Javkhlantugs N, Inoue R, Itoh Y, Endo H, Tuzi S, Saitô H, Ueda K, Naito A. Role of aromatic residues in amyloid fibril formation of human calcitonin by solid-state 13C NMR and molecular dynamics simulation. Phys Chem Chem Phys 2013; 15:8890-901. [DOI: 10.1039/c3cp44544e] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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17
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Rawat A, Kumar D. NMR investigations of structural and dynamics features of natively unstructured drug peptide - salmon calcitonin: implication to rational design of potent sCT analogs. J Pept Sci 2012. [DOI: 10.1002/psc.2471] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Atul Rawat
- Centre of Biomedical Magnetic Resonance; Sanjay Gandhi Post-Graduate Institute of Medical Sciences Campus, Raibareli Road; Lucknow-; 226014; India
| | - Dinesh Kumar
- Centre of Biomedical Magnetic Resonance; Sanjay Gandhi Post-Graduate Institute of Medical Sciences Campus, Raibareli Road; Lucknow-; 226014; India
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Usachev KS, Efimov SV, Yulmetov AR, Filippov AV, Antzutkin ON, Afonin S, Klochkov VV. Spatial structure of heptapeptide Aβ(16-22) (beta-amyloid Aβ(1-40) active fragment) in solution and in complex with a biological membrane model. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2012; 50:784-792. [PMID: 23034896 DOI: 10.1002/mrc.3880] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 06/29/2012] [Accepted: 09/04/2012] [Indexed: 06/01/2023]
Abstract
The spatial structure of an active fragment of beta-amyloid Aβ(1-40) heptapeptide Aβ(16-22) (Lys-Leu-Val-Phe-Phe-Ala-Glu) in aqueous buffer solution and in complex with sodium dodecyl sulfate micelles as a model membrane system was investigated by (1)H NMR spectroscopy and two-dimensional NMR (TOCSY, HSQC-HECADE (Heteronuclear Couplings from ASSCI-domain experiments with E.COSY-type crosspeaks), NOESY) spectroscopy. Complex formation was confirmed by the chemical shift changes of the heptapeptide's (1)H NMR spectra, as well as by the signs and values of the NOE effects in different environments. We compared the spatial structure of the heptapeptide in borate buffer solution and in complex with a model of the cell surface membrane.
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Affiliation(s)
- Konstantin S Usachev
- Kazan (Volga Region) Federal University, 18 Kremlevskaya St., 420008, Kazan, Russian Federation
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The structure of secretin family GPCR peptide ligands: implications for receptor pharmacology and drug development. Drug Discov Today 2012; 17:1006-14. [PMID: 22579744 DOI: 10.1016/j.drudis.2012.05.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 04/03/2012] [Accepted: 05/04/2012] [Indexed: 11/23/2022]
Abstract
The secretin family G protein-coupled receptors, characterized by a large N-terminal extracellular domain and seven transmembrane helices, are drug targets in many diseases, including migraine, cardiovascular disease, diabetes, osteoporosis and inflammatory disorders. Their activating ligands are peptides with an average length of 30 amino acids. In this article we review the available structural data for these peptides and how this explains their activity. We emphasize how this information may be used to accelerate the development of new drugs against these receptors.
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Bijani C, Arnarez C, Brasselet S, Degert C, Broussaud O, Elezgaray J, Dufourc EJ. Stability and structure of protein-lipoamino acid colloidal particles: toward nasal delivery of pharmaceutically active proteins. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:5783-5794. [PMID: 22394194 DOI: 10.1021/la300222v] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
To circumvent the painful intravenous injection of proteins in the treatment of children with growth deficiency, anemia, and calcium insufficiency, we investigated the stability and structure of protein-lipoamino acid complexes that could be nasally sprayed. Preparations that ensure a colloidal and structural stability of recombinant human growth hormone (rhGH), recombinant human erythropoietin (rhEPO), and salmon calcitonin (sCT) mixed with lauroyl proline (LP) were established. Protein structure was controlled by circular dichroism, and very small sizes of ca. 5 nm were determined by dynamic light scattering. The colloidal preparations could be sprayed with a droplet size of 20-30 μm. The molecular structure of aggregates was investigated by all-atom molecular dynamics. Whereas a lauroyl proline capping of globular proteins rhGH and rhEPO with preservation of their active structure was observed, a mixed micelle of sCT and lipoamino acids was formed. In the latter, aggregated LP constitutes the inner core and the surface is covered with calcitonins that acquire a marked α-helix character. Hydrophobic/philic interaction balance between proteins and LP drives the particles' stability. Passage through nasal cells grown at confluence was markedly increased by the colloidal preparations and could reach a 20 times increase in the case of EPO. Biological implications of such colloidal preparations are discussed in terms of furtiveness.
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Affiliation(s)
- Christian Bijani
- Institute of Chemistry & Biology of Membranes & Nanoobjects, UMR 5248, CNRS, Université Bordeaux, Institut Polytechnique Bordeaux, Pessac, France
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21
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Purdue BW, Tilakaratne N, Sexton PM. Molecular Pharmacology of the Calcitonin Receptor. ACTA ACUST UNITED AC 2011. [DOI: 10.3109/10606820213681] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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22
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Nanga RPR, Brender JR, Vivekanandan S, Ramamoorthy A. Structure and membrane orientation of IAPP in its natively amidated form at physiological pH in a membrane environment. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2337-42. [PMID: 21723249 DOI: 10.1016/j.bbamem.2011.06.012] [Citation(s) in RCA: 207] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Revised: 06/09/2011] [Accepted: 06/14/2011] [Indexed: 11/25/2022]
Abstract
Human islet amyloid polypeptide is a hormone coexpressed with insulin by pancreatic beta-cells. For reasons not clearly understood, hIAPP aggregates in type II diabetics to form oligomers that interfere with beta-cell function, eventually leading to the loss of insulin production. The cellular membrane catalyzes the formation of amyloid deposits and is a target of amyloid toxicity through disruption of the membrane's structural integrity. Therefore, there is considerable current interest in solving the 3D structure of this peptide in a membrane environment. NMR experiments could not be directly utilized in lipid bilayers due to the rapid aggregation of the peptide. To overcome this difficulty, we have solved the structure of the naturally occurring peptide in detergent micelles at a neutral pH. The structure has an overall kinked helix motif, with residues 7-17 and 21-28 in a helical conformation, and with a 3(10) helix from Gly 33-Asn 35. In addition, the angle between the N- and C-terminal helices is constrained to 85°. The greater helical content of human IAPP in the amidated versus free acid form is likely to play a role in its aggregation and membrane disruptive activity.
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Nanga RPR, Brender JR, Xu J, Hartman K, Subramanian V, Ramamoorthy A. Three-dimensional structure and orientation of rat islet amyloid polypeptide protein in a membrane environment by solution NMR spectroscopy. J Am Chem Soc 2009; 131:8252-61. [PMID: 19456151 PMCID: PMC4163022 DOI: 10.1021/ja9010095] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Islet amyloid polypeptide (IAPP or amylin) is a 37-residue peptide hormone associated with glucose metabolism that is cosecreted with insulin by beta-cells in the pancreas. Since human IAPP is a highly amyloidogenic peptide, it has been suggested that the formation of IAPP amyloid fibers is responsible for the death of beta-cells during the early stages of type II diabetes. It has been hypothesized that transient membrane-bound alpha-helical structures of human IAPP are precursors to the formation of these amyloid deposits. On the other hand, rat IAPP forms transient alpha-helical structures but does not progress further to form amyloid fibrils. To understand the nature of this intermediate state and the difference in toxicity between the rat and human versions of IAPP, we have solved the high-resolution structure of rat IAPP in the membrane-mimicking detergent micelles composed of dodecylphosphocholine. The structure is characterized by a helical region spanning the residues A5 to S23 and a disordered C-terminus. A distortion in the helix is seen at R18 and S19 that may be involved in receptor binding. Paramagnetic quenching NMR experiments indicate that rat IAPP is bound on the surface of the micelle, in agreement with other nontoxic forms of IAPP. A comparison to the detergent-bound structures of other IAPP variants indicates that the N-terminal region may play a crucial role in the self-association and toxicity of IAPP by controlling access to the putative dimerization interface on the hydrophobic face of the amphipathic helix.
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Cheng W, Lim LY. Comparison of Reversible and Nonreversible Aqueous-Soluble Lipidized Conjugates of Salmon Calcitonin. Mol Pharm 2008; 5:610-21. [DOI: 10.1021/mp8000167] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Weiqiang Cheng
- Department of Pharmacy, National University of Singapore, 18 Science Drive 4, Singapore 117543, and Pharmacy, School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Lee-Yong Lim
- Department of Pharmacy, National University of Singapore, 18 Science Drive 4, Singapore 117543, and Pharmacy, School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
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Cheng W, Satyanarayanajois S, Lim LY. Aqueous-Soluble, Non-Reversible Lipid Conjugate of Salmon Calcitonin: Synthesis, Characterization and In Vivo Activity. Pharm Res 2006; 24:99-110. [PMID: 17109213 DOI: 10.1007/s11095-006-9128-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Accepted: 07/18/2006] [Indexed: 10/23/2022]
Abstract
PURPOSE A novel, non-reversible, aqueous-based lipidization strategy with palmitic acid as a model lipid was evaluated for conjugation with salmon calcitonin (sCT). MATERIALS AND METHODS A water-soluble epsilon-maleimido lysine derivative of palmitic acid was synthesized from reaction of palmitic acid N-succinimidyl ester and epsilon-maleimido lysine. The latter was generated from reaction of alpha-Boc-lysine and methylpyrrolecarboxylate, with subsequent deprotection of the Boc group. The palmitic derivative was further conjugated with sCT via a thio-ether bond to produce Mal-sCT in aqueous solution. The identity and purity of Mal-sCT was confirmed by Electrospray Ionisation Mass spectrometry (ESI-MS) and HPLC. RESULTS Yield of Mal-sCT was 83%. Dynamic light scattering and circular dichroism data suggested that Mal-sCT presented as a stable helical structure in aqueous solutions of varying polarity, with a propensity to aggregate at concentrations above 11 microM. Cellular uptake of Mal-sCT was twice that of sCT in the Caco-2 cell model, and the conjugate was more resistant to liver enzyme degradation. Mal-sCT exhibited comparable hypocalcemic activity to sCT when administered subcutaneously in the rat model at sCT equivalent dose of 0.114 mg/kg. Peroral Mal-sCT, however, produced variability in therapeutic outcome. While four out of six rats did not respond following intragastric gavage with Mal-sCT, two rats showed significantly suppressed plasma calcium levels (approximately 60% of baseline) for up to 10 h. CONCLUSION A novel non-reversible, water-soluble lipid conjugate of sCT was successfully synthesized that showed (1) different aggregation behavior and secondary structure, (2) improved enzymatic stability and cellular uptake, and (3) comparable hypocalcemic activity in vivo compared to sCT.
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Affiliation(s)
- Weiqiang Cheng
- Department of Pharmacy, National University of Singapore, 18 Science Drive 4, Singapore, 117543, Singapore
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26
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Andreotti G, Méndez BL, Amodeo P, Morelli MAC, Nakamuta H, Motta A. Structural Determinants of Salmon Calcitonin Bioactivity. J Biol Chem 2006; 281:24193-203. [PMID: 16766525 DOI: 10.1074/jbc.m603528200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Salmon calcitonin (sCT) forms an amphipathic helix in the region 9-19, with the C-terminal decapeptide interacting with the helix (Amodeo, P., Motta, A., Strazzullo, G., Castiglione Morelli, M. A. (1999) J. Biomol. NMR 13, 161-174). To uncover the structural requirements for the hormone bioactivity, we investigated several sCT analogs. They were designed so as to alter the length of the central helix by removal and/or replacement of flanking residues and by selectively mutating or deleting residues inside the helix. The helix content was assessed by circular dichroism and NMR spectroscopies; the receptor binding affinity in human breast cancer cell line T 47D and the in vivo hypocalcemic activity were also evaluated. In particular, by NMR spectroscopy and molecular dynamics calculations we studied Leu(23),Ala(24)-sCT in which Pro(23) and Arg(24) were replaced by helix inducing residues. Compared with sCT, it assumes a longer amphipathic alpha-helix, with decreased binding affinity and one-fifth of the hypocalcemic activity, therefore supporting the idea of a relationship between a definite helix length and bioactivity. From the analysis of other sCT mutants, we inferred that the correct helix length is located in the 9-19 region and requires long range interactions and the presence of specific regions of residues within the sequence for high binding affinity and hypocalcemic activity. Taken together, the structural and biological data identify well defined structural parameters of the helix for sCT bioactivity.
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Affiliation(s)
- Giuseppina Andreotti
- Istituto di Chimica Biomolecolare del Consiglio Nazionale delle Ricerche, Comprensorio Olivetti, Edificio A, 80078 Pozzuoli (Napoli), Italy
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27
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Liu D, Yao H, Chen Y, Feng Y, Chen Y, Wang J. The N-terminal 26-residue fragment of human programmed cell death 5 protein can form a stable alpha-helix having unique electrostatic potential character. Biochem J 2006; 392:47-54. [PMID: 16083422 PMCID: PMC1317663 DOI: 10.1042/bj20050688] [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: 11/17/2022]
Abstract
PDCD5-(1-26) is a N-terminal 26-residue fragment of human PDCD5 (programmed cell death 5) protein. PDCD5 is an important novel protein that regulates both apoptotic and non-apoptotic programmed cell death. The conformation of PDCD5 protein is a stable helical core consisting of a triple-helix bundle and two dissociated terminal regions. The N-terminal region is ordered and contains abundant secondary structure. Overexpression and purification of the N-terminal 26-residure fragment, PDCD5-(1-26), was performed in this study to better understand its tertiary structure. The spectroscopic studies using CD and hetero- and homo-nuclear NMR methods determine a stable alpha-helix formed by Asp3-Ala19 of PDCD5-(1-26). The N-terminal residues Asp3-Ala19 of PDCD5 were then affirmed to have the capacity to form a stable alpha-helix independently of the core of the protein. Analysis of the helical peptide of PDCD5-(1-26) indicates that the surface of this well-formed alpha-helix has a unique electrostatic potential character. This may provide an environment for the N-terminal alpha-helix of PDCD5 to serve as an independent functional entity of the protein. The apoptosis activity assay shows that the deletion of the N-terminal alpha-helix of PDCD5 significantly attenuates the apoptosis-promoting effects on HL-60 cells induced by serum withdrawal.
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Affiliation(s)
- Dongsheng Liu
- *National Laboratory of Biomacromolecules, Center for Molecular Biology, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Hongwei Yao
- *National Laboratory of Biomacromolecules, Center for Molecular Biology, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Yaoyao Chen
- †Laboratory of Medical Immunology, School of Basic Medical Science, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100083, China
| | - Yingang Feng
- *National Laboratory of Biomacromolecules, Center for Molecular Biology, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Yingyu Chen
- †Laboratory of Medical Immunology, School of Basic Medical Science, Peking University Health Science Center, 38 Xueyuan Road, Beijing 100083, China
| | - Jinfeng Wang
- *National Laboratory of Biomacromolecules, Center for Molecular Biology, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
- To whom correspondence should be addressed (email address: )
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28
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Stevenson CL, Bennett DB, Lechuga-Ballesteros D. Pharmaceutical liquid crystals: the relevance of partially ordered systems. J Pharm Sci 2006; 94:1861-80. [PMID: 16052511 DOI: 10.1002/jps.20435] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Pharmaceutical solids have generally been characterized as either three-dimensional crystals or amorphous solids based on X-ray powder diffraction and modulated temperature differential scanning calorimetry. In contrast, fewer examples of thermotropic and lyotropic liquid crystals, or mesophases, appear in the pharmaceutical literature, and that literature teaches that the aforementioned analytical techniques should be complemented with polarized light microscopy and small-angle X-ray scattering in order to effectively identify potential liquid crystalline states. Lyotropic liquid crystals are induced by the presence of solvent, and have been extensively described elsewhere in the context of emulsion technology; however, other pharmaceutical examples are emerging. Thermotropic liquid crystals are induced by a change in temperature and are essentially free of solvent, where more pharmaceutical applications appear in the literature. In the present review the general structural characteristics that favor the formation of liquid crystalline mesophases are categorized by therapeutic target and molecular size, and the analytical means of their identification are presented.
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Pham V, Dong M, Wade JD, Miller LJ, Morton CJ, Ng HL, Parker MW, Sexton PM. Insights into interactions between the alpha-helical region of the salmon calcitonin antagonists and the human calcitonin receptor using photoaffinity labeling. J Biol Chem 2005; 280:28610-22. [PMID: 15929987 DOI: 10.1074/jbc.m503272200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fish-like calcitonins (CTs), such as salmon CT (sCT), are widely used clinically in the treatment of bone-related disorders; however, the molecular basis for CT binding to its receptor, a class II G protein-coupled receptor, is not well defined. In this study we have used photoaffinity labeling to identify proximity sites between CT and its receptor. Two analogues of the antagonist sCT(8-32) containing a single photolabile p-benzoyl-l-phenylalanine (Bpa) residue in position 8 or 19 were used. Both analogues retained high affinity for the CT receptor and potently inhibited agonist-induced cAMP production. The [Bpa(19)]sCT(8-32) analogue cross-linked to the receptor at or near the equivalent cross-linking site of the full-length peptide, within the fragment Cys(134)-Lys(141) (within the amino terminus of the receptor, adjacent to transmembrane 1) (Pham, V., Wade, J. D., Purdue, B. W., and Sexton, P. M. (2004) J. Biol. Chem. 279, 6720-6729). In contrast, proteolytic mapping and mutational analysis identified Met(49) as the cross-linking site for [Bpa(8)]sCT(8-32). This site differed from the previously identified cross-linking site of the agonist [Bpa(8)]human CT (Dong, M., Pinon, D. I., Cox, R. F., and Miller, L. J. (2004) J. Biol. Chem. 279, 31177-31182) and may provide evidence for conformational differences between interaction with active and inactive state receptors. Molecular modeling suggests that the difference in cross-linking between the two Bpa(8) analogues can be accounted for by a relatively small change in peptide orientation. The model was also consistent with cooperative interaction between the receptor amino terminus and the receptor core.
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Affiliation(s)
- Vi Pham
- Howard Florey Institute, The University of Melbourne, Victoria 3010, Australia
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30
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Tyndall JDA, Pfeiffer B, Abbenante G, Fairlie DP. Over One Hundred Peptide-Activated G Protein-Coupled Receptors Recognize Ligands with Turn Structure. Chem Rev 2005; 105:793-826. [PMID: 15755077 DOI: 10.1021/cr040689g] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Joel D A Tyndall
- Center for Drug Design and Development, Institute for Molecular Bioscience, University of Queensland, Brisbane, Qld 4072, Australia
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31
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Micelli S, Meleleo D, Picciarelli V, Stoico MG, Gallucci E. Effect of nanomolar concentrations of sodium dodecyl sulfate, a catalytic inductor of alpha-helices, on human calcitonin incorporation and channel formation in planar lipid membranes. Biophys J 2005; 87:1065-75. [PMID: 15298911 PMCID: PMC1304447 DOI: 10.1529/biophysj.103.037200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human Calcitonin (hCt) is a peptide hormone which has a regulatory action in calcium-phosphorus metabolism. It is currently used as a therapeutic tool in bone pathologies such as osteoporosis and Paget's disease. However, due to its amphiphilic property tends to form a gelatinous solution in water which consists of fibrils that limits its therapeutic use. Here we show that sodium dodecyl sulfate (SDS), an anionic detergent able to induce and stabilize alpha-helices in polypeptides, at a monomeric concentration ranging between 0.26 mM-5 pM (all concentrations are below the CMC), increases the rate and number of hCt channel formation in planar lipid membranes, at both high and low hCt concentrations, with a maximum increase at a molecular hCt/SDS ratio of 1000:1. This effect could be interpreted as a counteraction to the fibrillation process of hCt molecules by removing molecules available for aggregation from the fluid; furthermore, this action, independently of channel formation in the cell membrane, could improve the peptide-receptor interaction. The action of SDS could be attributable to the strength of the sulfate negative charge and the hydrophobic chain; in fact, a similar effect was obtained with lauryl sarcosine and not with a neutral detergent such as n-dodecyl-beta-D-maltoside. The very low molecular ratio between SDS and peptide is suggestive of a possible catalytic action of SDS that could induce alpha-helices, the appropriate structures for interacting with the membrane. Moreover, in the experimental conditions investigated, the addition of SDS does not modify the membrane's electrical properties and most of the channel properties. This finding may contribute to the knowledge of environment-folding diseases due to protein and peptides.
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Affiliation(s)
- Silvia Micelli
- Dipartimento Farmaco-Biologico, Dipartimento Interateneo di Fisica, Università degli Studi di Bari, I-70126 Bari, Italy
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Nabuchi Y, Asoh Y, Takayama M. Folding analysis of hormonal polypeptide calcitonins and the oxidized calcitonins using electrospray ionization mass spectrometry combined with H/D exchange. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2004; 15:1556-1564. [PMID: 15519222 DOI: 10.1016/j.jasms.2004.07.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2004] [Revised: 07/06/2004] [Accepted: 07/12/2004] [Indexed: 05/24/2023]
Abstract
Conformational change of calcitonins has been examined by measuring the rate of hydrogen/deuterium (H/D) exchange in amino acids. Time dependent m/z shift caused by H/D exchange was monitored by electrospray ionization quadrupole ion trap mass spectrometry (ESI-QIT MS). The rate constants of H/D exchange were calculated from apparent first-order kinetics. The time course of H/D exchange exhibited two phases of faster and slower exchange. The smaller rate constant (k2) estimated from the slower H/D exchange was correlated with an alpha-helix content that reflected the folding state. The order of k2 values obtained for human calcitonin (hCT), porcine calcitonin (pCT), salmon calcitonin (sCT), and elcatonin (ECT) was hCT > pCT approximately sCT > ECT. Although the amino acid sequence of sCT is similar to that of ECT, their k2 values were considerably different. The results suggest that ECT is relatively rigid on the N-terminal side cyclic structure in the folded state. Further, the effect of methionine oxidation on k2 has been examined. In the oxidized pCT that possesses similar biological activity with the intact pCT, the k2 values obtained were nearly equal. The k2 of hCT increased via methionine oxidation, and the biological activity was weakened by oxidation. This suggested that methionine oxidation of hCT produced unfolding in the secondary structure and that oxidative unfolding of hCT led to the loss of biological activity. The results indicate that the H/D exchange rate constant may be used as an informative parameter to elucidate the relationship between the folded state and biological activity of polypeptides like calcitonins with secondary structure.
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Affiliation(s)
- Yoshiaki Nabuchi
- Fuji Gotemba Research Laboratories, Chugai Pharmaceutical Co., Ltd., Gotemba, Japan.
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Wagner K, Van Mau N, Boichot S, Kajava AV, Krauss U, Le Grimellec C, Beck-Sickinger A, Heitz F. Interactions of the human calcitonin fragment 9-32 with phospholipids: a monolayer study. Biophys J 2004; 87:386-95. [PMID: 15240473 PMCID: PMC1304360 DOI: 10.1529/biophysj.103.036921] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2003] [Accepted: 03/26/2004] [Indexed: 11/18/2022] Open
Abstract
Human calcitonin and its C-terminal fragment 9-32 (hCT(9-32)) administered in a spray translocate into respiratory nasal epithelium with an effect similar to intravenous injection. hCT(9-32) is an efficient carrier to transfer the green fluorescent protein into excised bovine nasal mucosa. To understand the translocation of hCT(9-32) across plasma membranes, we investigated its interactions with phospholipids and its interfacial structure using model lipid monolayers. A combination of physicochemical methods was applied including surface tension measurements on adsorbed and spread monolayers at the air-water interface, Fourier transform infrared, circular dichroism, and atomic force microscopy on Langmuir-Blodgett monolayers. The results disclose that hCT(9-32) preferentially interacts with negatively charged phospholipids and does not insert spontaneously into lipid monolayers. This supports a nonreceptor-mediated endocytic internalization pathway as previously suggested. Structural studies revealed a random coil conformation of hCT(9-32) in solution, transforming to alpha-helices when the peptide is localized at lipid-free or lipid-containing air-water interfaces. Atomic force microscopy studies of monolayers of the peptide alone or mixed with dioleoylphosphatidylcholine revealed that hCT(9-32) forms filaments rolled into spirals. In contrast, when interacting with dioleoylphosphatidylglycerol, hCT(9-32) does not adopt filamentous structures. A molecular model and packing is proposed for the spiral-forming hCT(9-32).
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Affiliation(s)
- Kerstin Wagner
- Centre de Recherches de Biochimie Macromoléculaire-Centre National de la Recherche Scientifique, Formation de Recherche en Evolution 2593, F-34293 Montpellier Cedex, France
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Wang Y, Dou H, Cao C, Zhang N, Ma J, Mao J, Wu H. Solution structure and biological activity of recombinant salmon calcitonin S-sulfonated analog. Biochem Biophys Res Commun 2003; 306:582-9. [PMID: 12804605 DOI: 10.1016/s0006-291x(03)01028-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Salmon calcitonin S-sulfonated analog (abbreviated as [S-SO(3)(-)]rsCT) was prepared by introducing two sulfonic groups into the side chains of Cys1 and Cys7 of recombinant salmon calcitonin. The hypocalcemic potency of this open-chain analog is 5500IU/mg, which is about 30% higher than that (4500IU/mg) of the wild type. The solution conformation of [S-SO(3)(-)]rsCT was studied in aqueous trifluoroethanol solution by CD, 2D-NMR spectroscopy, and distance geometry calculations. In the mixture of 60% TFE and 40% water, the peptide assumes an amphipathic alpha-helix in the region of residues 4-22, which is one turn longer than that of the native sCT. The structural feature analysis of the peptide revealed the presence of hydrophobic surface composed of five hydrophobic side chains of residues Leu4, Leu9, Leu12, Leu16, and Leu19, and a network of salt-bridges that consisted of a tetrad of oppositely charged side chains (Cys7-SO(3)(-)-Lys11(+)-Glu15(-)-Lys18(+)). The multiple salt bridges resulted in the stabilization of the longer amphipathic alpha-helix. Meanwhile, the higher hypocalcemic potency of the peptide could be attributed to the array of hydrophobic side chains of five leucine residues of the amphipathic alpha-helix.
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Affiliation(s)
- Yuefeng Wang
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, 200032, Shanghai, PR China
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35
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Reches M, Porat Y, Gazit E. Amyloid fibril formation by pentapeptide and tetrapeptide fragments of human calcitonin. J Biol Chem 2002; 277:35475-80. [PMID: 12095997 DOI: 10.1074/jbc.m206039200] [Citation(s) in RCA: 257] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The process of amyloid fibril formation by the human calcitonin hormone is associated with medullary thyroid carcinoma. Based on the effect of pH on the fibrillization of human calcitonin, the analysis of conformationally constrained analogues of the hormone, and our suggestion regarding the role of aromatic residues in the process of amyloid fibril formation, we studied the ability of a short aromatic charged peptide fragment of calcitonin (NH(2)-DFNKF-COOH) to form amyloid fibrils. Here, using structural and biophysical analysis, we clearly demonstrate the ability of this short peptide to form well ordered amyloid fibrils. A shorter truncated tetrapeptide, NH(2)-DFNK-COOH, also formed fibrils albeit less ordered than those formed by the pentapeptide. We could not detect amyloid fibril formation by the NH(2)-FNKF-COOH tetrapeptide, the NH(2)-DFN-COOH tripeptide, or the NH(2)-DANKA-COOH phenylalanine to the alanine analogue of the pentapeptide. The formation of amyloid fibrils by rather hydrophilic peptides is quite striking, because it was speculated that hydrophobic interactions might play a key role in amyloid formation. This is the first reported case of fibril formation by a peptide as short as a tetrapeptide and one of very few cases of amyloid formation by pentapeptides. Because the aromatic nature seems to be the only common property of the various very short amyloid-forming peptides, it further supports our hypothesis on the role of aromatic interactions in the process of amyloid fibril formation.
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Affiliation(s)
- Meital Reches
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 69978, Israel
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36
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Stipani V, Gallucci E, Micelli S, Picciarelli V, Benz R. Channel formation by salmon and human calcitonin in black lipid membranes. Biophys J 2001; 81:3332-8. [PMID: 11720996 PMCID: PMC1301790 DOI: 10.1016/s0006-3495(01)75966-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In this study we investigated the interaction of salmon and human calcitonin (Ct) with artificial lipid bilayer membranes. Both peptides were able to form either transient or permanent channels in the model membranes. The channels formed by salmon Ct at concentration (125 nM) had, on average, a single-channel conductance of 0.58 +/- 0.04 nS in 1M KCl (+10 mV), which is voltage-dependent at lower voltages. Human Ct forms at the same concentration channels with a much lower probability, and high voltages of up to +150 mV were needed to initiate channel formation. The estimated single-channel conductance formed under these conditions was approximately 0.0119 +/- 0.0003 nS in 1 M KCl. Both salmon and human Ct channels were found to be permeable to calcium ions. The possibility is discussed that the superior therapeutic effect of salmon Ct as a tool to treat bone disorders, including Paget disease, osteoporosis, and hypercalcemia of malignancy, rather than human Ct is related to the lack of the fibrillating property of salmon Ct. Preliminary data indicate that also eel and porcine Ct and carbocalcitonin form channels in model membranes.
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Affiliation(s)
- V Stipani
- Dept. Farmaco-Biologico, Università degli Studi di Bari, I-70126 Bari, Italy
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37
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Cooper GJS. Amylin and Related Proteins: Physiology and Pathophysiology. Compr Physiol 2001. [DOI: 10.1002/cphy.cp070210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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38
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Kamihira M, Naito A, Tuzi S, Nosaka AY, Saitô H. Conformational transitions and fibrillation mechanism of human calcitonin as studied by high-resolution solid-state 13C NMR. Protein Sci 2000; 9:867-77. [PMID: 10850796 PMCID: PMC2144639 DOI: 10.1110/ps.9.5.867] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Conformational transitions of human calcitonin (hCT) during fibril formation in the acidic and neutral conditions were investigated by high-resolution solid-state 13C NMR spectroscopy. In aqueous acetic acid solution (pH 3.3), a local alpha-helical form is present around Gly10 whereas a random coil form is dominant as viewed from Phe22, Ala26, and Ala31 in the monomer form on the basis of the 13C chemical shifts. On the other hand, a local beta-sheet form as viewed from Gly10 and Phe22, and both beta-sheet and random coil as viewed from Ala26 and Ala31 were detected in the fibril at pH 3.3. The results indicate that conformational transitions from alpha-helix to beta-sheet, and from random coil to beta-sheet forms occurred in the central and C-terminus regions, respectively, during the fibril formation. The increased 13C resonance intensities of fibrils after a certain delay time suggests that the fibrillation can be explained by a two-step reaction mechanism in which the first step is a homogeneous association to form a nucleus, and the second step is an autocatalytic heterogeneous fibrillation. In contrast to the fibril at pH 3.3, the fibril at pH 7.5 formed a local beta-sheet conformation at the central region and exhibited a random coil at the C-terminus region. Not only a hydrophobic interaction among the amphiphilic alpha-helices, but also an electrostatic interaction between charged side chains can play an important role for the fibril formation at pH 7.5 and 3.3 acting as electrostatically favorable and unfavorable interactions, respectively. These results suggest that hCT fibrils are formed by stacking antiparallel beta-sheets at pH 7.5 and a mixture of antiparallel and parallel beta-sheets at pH 3.3.
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Affiliation(s)
- M Kamihira
- Department of Life Science, Himeji Institute of Technology, Harime Science Garden City, Kamigori, Hyogo, Japan
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39
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Stevenson CL, Tan MM. Solution stability of salmon calcitonin at high concentration for delivery in an implantable system. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2000; 55:129-39. [PMID: 10784029 DOI: 10.1034/j.1399-3011.2000.00160.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Salmon calcitonin solutions (50 mg/mL and 100 mg/mL) were placed on stability at 37 degrees C for 1 year in a variety of solvent systems including water, ethanol, glycerol, propylene glycol (PG) and dimethyl sulfoxide (DMSO). Calcitonin degradation was monitored by RP-HPLC and size-exclusion chromatography. DMSO and pH 3.3 solutions provided optimum stability. Conformational stability was also monitored by FTIR over the 1 year time course and compared with chemical and physical stability. After 12 months at 37 degrees C, four major conformations were observed: a beta-sheet conformation (pH 3.3, pH 5.0, 70% DMSO and 70% glycerol), an aggregate conformation (pH 7.0 water), a strong alpha-helical conformation (70% EtOH, 70% PG) and a weak alpha-helical conformation (100% DMSO). No correlation between structure and chemical stability was observed in which both the beta-sheet structure (pH 3.3, water) and a loose alpha-helical structure (100% DMSO) demonstrated good stability. However, some correlation was observed between structure and physical stability, where co-solvents inducing an alpha-helical structure resulted in a decrease in gelation. These two structural states associated with improved stability and minimal gelation, indicated that gelation can be reduced or eliminated by the use of pharmaceutically acceptable co-solvents. Finally, salmon calcitonin (50 mg/mL) was formulated in 100% DMSO and delivered from a DUROS implant over 4 months. Delivery at a target dose of 18 microg/day calcitonin at 37 degrees C was confirmed.
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40
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Tanaka A, Murata M, Fujiwara H. QSAR study of the peptidic fibrinogen inhibitors FK633, FR158999 and related derivatives, using a novel and useful hydrophobic descriptor (logPmw). Bioorg Med Chem Lett 1998; 8:2483-8. [PMID: 9873566 DOI: 10.1016/s0960-894x(98)00405-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A QSAR study using the novel hydrophobic descriptor (logPmw), which is a descriptor for membrane affinity, of our fibrinogen inhibitors FK633 (1), FR158999 (21), and related derivatives was performed, and resulted in good correlation (n = 19, s = 0.268, F = 6.38**, r = 0.667). Based on these results, we constructed a hypothesis by which these potent inhibitors bind to the receptor via the biomembrane and the C-terminal moiety functions as an anchor moiety.
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Affiliation(s)
- A Tanaka
- Basic Research Laboratories, Fujisawa Pharmaceutical Co. Ltd., Osaka, Japan
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41
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Kwon MY, Hong SY, Lee KH. Structure-activity analysis of brevinin 1E amide, an antimicrobial peptide from Rana esculenta. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1387:239-48. [PMID: 9748603 DOI: 10.1016/s0167-4838(98)00123-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Brevinin 1E, consisting of 24 amino acid residues, from Rana esculenta has potent antimicrobial and hemolytic activity. From a structural point of view, this peptide has a N-terminal hydrophobic region, a proline hinge region in the middle and a C-terminal loop region delineated by an intra-disulfide bridge, which is a common structural feature of antimicrobial peptides from Rana species. To investigate the structural features for antimicrobial and hemolytic activity, truncated and linearized brevinin 1E amides were synthesized and characterized. A deletion of three amino acids from the N-terminal region did not greatly affect antimicrobial activity but dramatically reduced hemolytic activity. The contribution of the intra-disulfide bridge to antimicrobial and hemolytic activity was somewhat different between brevinin 1E amide and truncated fragments. In brevinin 1E amide, the elimination of the intra-disulfide bridge did not greatly affect antimicrobial and hemolytic activity whereas the elimination of the intra-disulfide bridge in the truncated fragments did not decrease antimicrobial activity but did decrease hemolytic activity. Circular dichroism spectra and the retention time on the C18 reverse phase column revealed that the intra-disulfide bridge (i, i+6) formed an amphipathic loop which increased hydrophobicity and helped to induce the alpha-helical structure in the membrane-mimetic environment. Even though the intra-disulfide bridge and the N-terminal region were responsible for the alpha-helical structure and hydrophobicity, these two structural features were not essential for antimicrobial activity. The hemolytic activity of brevinin 1E amide and its analogs also correlated well with the retention time rather than the alpha-helicity.
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Affiliation(s)
- M Y Kwon
- Protein Chemistry Laboratory, Mogam Biotechnology Research Institute, 341 Pojung-Ri, Koosung-Myun, Yongin-City, Kyunggi-Do, 449-910, South Korea
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42
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Motta A, Andreotti G, Amodeo P, Strazzullo G, Morelli MAC. Solution structure of human calcitonin in membrane-mimetic environment: The role of the amphipathic helix. Proteins 1998. [DOI: 10.1002/(sici)1097-0134(19980815)32:3<314::aid-prot7>3.0.co;2-h] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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43
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Moriarty DF, Vagts S, Raleigh DP. A role for the C-terminus of calcitonin in aggregation and gel formation: a comparative study of C-terminal fragments of human and salmon calcitonin. Biochem Biophys Res Commun 1998; 245:344-8. [PMID: 9571152 DOI: 10.1006/bbrc.1998.8425] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calcitonin is used in therapy for osteoporosis and Paget's disease. In vitro, human calcitonin forms thick gels which limits its usefulness as a therapeutic, and consequently salmon calcitonin which is less prone to aggregate is commonly used instead. In order to probe the role of the C-terminal region of the molecule in association and gel formation we have prepared a set of three peptides corresponding to the C-terminal regions of salmon calcitonin, human calcitonin and a mutant of human calcitonin in which Pro-23 is substituted with Ala. The peptides are largely disordered in their monomeric state as judged by CD and FTIR. All three peptides aggregate and form gels. Both human peptides form a gel much faster than the salmon peptide and the proline to alanine mutant forms a gel faster than the wildtype human peptide. Gel formation by all three peptides is slower than for intact human calcitonin. CD indicates a difference in conformation for the human fragment but not for the salmon fragment between the monomeric state and the gel state. FTIR experiments suggest the presence of beta-structure in the gel derived from the human peptide but not in the gel derived from the salmon peptide. These results show that there are clear differences in the association properties of the peptides and point to a potential role for the C-terminal region of calcitonin in controlling aggregation/gel formation.
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Affiliation(s)
- D F Moriarty
- Department of Chemistry, State University of New York at Stony Brook 11794-3400, USA
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44
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Abstract
A function of the intra-disulfide bridge located at the C-terminal of Rana peptides has not been extensively studied. To investigate the function of the disulfide bridge related to the activity and the structure, we chose Gaegurin-6, isolated from Rana rugosa as a model peptide and synthesized linear analogs. The reduction of the disulfide bridge resulted in the complete loss of antimicrobial activity while replacements of cysteines by serines retained antimicrobial activity. Circular dichroism spectra from a titration of the peptides in sodium dodecyl sulfate indicated that the disulfide bridge of Gaegurin-6 might stabilize the induction of an alpha helical structure in lipid membranes and the alpha helical forming propensity of the peptides correlated with antimicrobial activity.
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Affiliation(s)
- K H Lee
- Protein Chemistry Laboratory, Mogam Biotechnology Research Institute, Kyunggi-Do, South Korea.
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45
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Abstract
A thermodynamic model describing formation of alpha-helices by peptides and proteins in the absence of specific tertiary interactions has been developed. The model combines free energy terms defining alpha-helix stability in aqueous solution and terms describing immersion of every helix or fragment of coil into a micelle or a nonpolar droplet created by the rest of protein to calculate averaged or lowest energy partitioning of the peptide chain into helical and coil fragments. The alpha-helix energy in water was calculated with parameters derived from peptide substitution and protein engineering data and using estimates of nonpolar contact areas between side chains. The energy of nonspecific hydrophobic interactions was estimated considering each alpha-helix or fragment of coil as freely floating in the spherical micelle or droplet, and using water/cyclohexane (for micelles) or adjustable (for proteins) side-chain transfer energies. The model was verified for 96 and 36 peptides studied by 1H-nmr spectroscopy in aqueous solution and in the presence of micelles, respectively ([set 1] and [set 2]) and for 30 mostly alpha-helical globular proteins ([set 3]). For peptides, the experimental helix locations were identified from the published medium-range nuclear Overhauser effects detected by 1H-nmr spectroscopy. For sets 1, 2, and 3, respectively, 93, 100, and 97% of helices were identified with average errors in calculation of helix boundaries of 1.3, 2.0, and 4.1 residues per helix and an average percentage of correctly calculated helix-coil states of 93, 89, and 81%, respectively. Analysis of adjustable parameters of the model (the entropy and enthalpy of the helix-coil transition, the transfer energy of the helix backbone, and parameters of the bound coil), determined by minimization of the average helix boundary deviation for each set of peptides or proteins, demonstrates that, unlike micelles, the interior of the effective protein droplet has solubility characteristics different from that for cyclohexane, does not bind fragments of coil, and lacks interfacial area.
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Affiliation(s)
- A L Lomize
- College of Pharmacy, University of Michigan, Ann Arbor 48109, USA
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46
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Koskinen AM, Valo T, Vihavainen S, Hakala JM. Synthesis of α-helix substituted analogs of calcitonin gene-related peptide. Bioorg Med Chem Lett 1995. [DOI: 10.1016/0960-894x(95)00078-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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47
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Wray V, Federau T, Henklein P, Klabunde S, Kunert O, Schomburg D, Schubert U. Solution structure of the hydrophilic region of HIV-1 encoded virus protein U (Vpu) by CD and 1H NMR spectroscopy. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1995; 45:35-43. [PMID: 7775007 DOI: 10.1111/j.1399-3011.1995.tb01565.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The HIV-1 specific Vpu is a class I oligomeric membrane phosphoprotein of unknown structure and mechanism. The first experimental evidence for the position of secondary structural elements present in the hydrophilic C-terminal region of Vpu under various solution regimes is reported. CD data for nine overlapping 15 amino-acid fragments and 3 longer fragments indicate the presence of only transitory amounts of stable structure in aqueous solution alone, while with increasing trifluoroethanol content limiting structures were found indicating two helical segments in the hydrophilic region of Vpu. These limiting structures were more precisely defined from a detailed study of Vpu41-58, Vpu52-74 and Vpu63-81, by a combination of 2D 1H NMR spectroscopy, distance geometry, and restrained molecular dynamics and energy minimization calculations. Sets of low-energy conformations compatible with the quantitative NOE data indicate that Vpu41-58 has an alpha-helix from residues 42 to 50 while a second helix is found for Vpu52-74 from residues 57 to 69. Vpu63-81 shows only the presence of a single reverse turn at residues 74 to 77, without any evidence of helix, under the same conditions. From CD measurements the first helix extends back to residue 30 and is connected to the N-terminal anchor of Vpu. Thus the hydrophilic region of Vpu consists of two alpha-helices joined by a flexible region of 6 or 7 residues, which contains the phosphoacceptor sites of Vpu at positions 52 and 56. The second helix is followed by a single reverse turn and a flexible C-terminus.
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Affiliation(s)
- V Wray
- Department of Molecular Structure Research, Institute of Biotechnological Research, Braunschweig, Germany
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Ogawa K, Nishimura S, Doi M, Kyogoku Y, Hayashi M, Kobayashi Y. Conformational analysis of elcatonin in solution. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 222:659-66. [PMID: 8020504 DOI: 10.1111/j.1432-1033.1994.tb18910.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The conformational characteristics of elcatonin, an analogue of eel calcitonin having a disulfide bond Cys1-Cys7 replaced by an ethylene linkage between residues 1 and 7, have been analyzed in aqueous trifluoroethanol solutions. Circular dichroic spectra of elcatonin and eel calcitonin itself reveal the presence of alpha-helices at trifluoroethanol concentrations above 15%. The spectral changes caused by the trifluoroethanol content of the solutions are interesting. An isosbetic point is detected for eel calcitonin indicating that a conformational transition occurs between two states, namely alpha-helical and random coil states. On the other hand, the CD curves of elcatonin at less than 15% trifluoroethanol deviate from the isosbetic point while those at higher concentration are similar to those of eCT. This can probably be attributed to the third element of the ordered structure of elcatonin which is formed in 15% trifluoroethanol. The solution conformation of elcatonin in a mixture of 60% water and 40% trifluoroethanol has been determined by the combined use of 1H-NMR spectroscopy and distance geometry calculations. The conformation is characterized by an amphiphilic alpha-helix between Thr6 and Thr21, which extends into the constrained cyclic portion of the molecule to Thr6. The third structural element of elcatonin found in the CD analysis is detected by some turn structures in the region between residue 1 and Ser5 in the calculated structure.
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Affiliation(s)
- K Ogawa
- Institute for Protein Research, Osaka University, Japan
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49
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Abstract
Membrane protein structure is difficult to determine by any technique. NMR spectroscopy of membrane proteins in solution can proceed using methods identical to those that have been successfully applied to numerous water-soluble proteins providing suitable solubilization conditions can be found. Organic solvents and small detergent micelles have correlation times short enough for structure determination based on 1H NOEs. Although it is difficult to generalize as each system is unique, organic solvents and micelles of strong detergents such as SDS are useful for amphiphilic peptides and small membrane proteins, whereas larger proteins need milder treatment to preserve the tertiary structure. Small unilamellar phospholipid vesicles are much too large for NOE-based structure determination, but they still fall under the domain of solution-state NMR and can be useful in certain circumstances.
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Affiliation(s)
- G D Henry
- Department of Biochemistry, University of Alberta, Edmonton, Canada
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50
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Arvinte T, Drake A. Comparative study of human and salmon calcitonin secondary structure in solutions with low dielectric constants. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53267-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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