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Garanger E, MacEwan SR, Sandre O, Brûlet A, Bataille L, Chilkoti A, Lecommandoux S. Structural Evolution of a Stimulus-Responsive Diblock Polypeptide Micelle by Temperature Tunable Compaction of its Core. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b01371] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Elisabeth Garanger
- Laboratoire
de Chimie des Polymères Organiques (LCPO), CNRS UMR 5629, Université de Bordeaux, Bordeaux-INP, Pessac 33607 Cedex, France
- Institut Européen de Chimie et Biologie (IECB), Pessac 33607, France
| | - Sarah R. MacEwan
- Department
of Biomedical Engineering, Duke University, Campus Box 90281, Durham, North Carolina 27708, United States
| | - Olivier Sandre
- Laboratoire
de Chimie des Polymères Organiques (LCPO), CNRS UMR 5629, Université de Bordeaux, Bordeaux-INP, Pessac 33607 Cedex, France
| | - Annie Brûlet
- Laboratoire
Léon Brillouin (LLB), CEA-CNRS UMR 12, CEA-Saclay, Gif-sur-Yvette 91191, France
| | - Laure Bataille
- Laboratoire
de Chimie des Polymères Organiques (LCPO), CNRS UMR 5629, Université de Bordeaux, Bordeaux-INP, Pessac 33607 Cedex, France
- Institut Européen de Chimie et Biologie (IECB), Pessac 33607, France
| | - Ashutosh Chilkoti
- Department
of Biomedical Engineering, Duke University, Campus Box 90281, Durham, North Carolina 27708, United States
| | - Sébastien Lecommandoux
- Laboratoire
de Chimie des Polymères Organiques (LCPO), CNRS UMR 5629, Université de Bordeaux, Bordeaux-INP, Pessac 33607 Cedex, France
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2
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Muiznieks LD, Reichheld SE, Sitarz EE, Miao M, Keeley FW. Proline-poor hydrophobic domains modulate the assembly and material properties of polymeric elastin. Biopolymers 2015; 103:563-73. [DOI: 10.1002/bip.22663] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 04/08/2015] [Accepted: 04/22/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Lisa D. Muiznieks
- Molecular Structure and Function Program, Research Institute, Hospital For Sick Children; 555 University Ave Toronto ON M5G1X8 Canada
| | - Sean E. Reichheld
- Molecular Structure and Function Program, Research Institute, Hospital For Sick Children; 555 University Ave Toronto ON M5G1X8 Canada
| | - Eva E. Sitarz
- Molecular Structure and Function Program, Research Institute, Hospital For Sick Children; 555 University Ave Toronto ON M5G1X8 Canada
| | - Ming Miao
- Molecular Structure and Function Program, Research Institute, Hospital For Sick Children; 555 University Ave Toronto ON M5G1X8 Canada
| | - Fred W. Keeley
- Molecular Structure and Function Program, Research Institute, Hospital For Sick Children; 555 University Ave Toronto ON M5G1X8 Canada
- Department of Biochemistry; University of Toronto; Toronto ON M5S1A8 Canada
- Department of Laboratory Medicine and Pathobiology; University of Toronto; Toronto ON M5S1A8 Canada
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3
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Bochicchio B, Pepe A, Crudele M, Belloy N, Baud S, Dauchez M. Tuning self-assembly in elastin-derived peptides. SOFT MATTER 2015; 11:3385-3395. [PMID: 25811498 DOI: 10.1039/c5sm00072f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Elastin-derived peptides are gaining increasing interest as potential biomaterials. Previous studies have demonstrated that short elastin-derived peptides are able to self-assemble into fibrils as the entire elastin protein. The motif responsible for that is the XGGZG motif at least three-fold repeated. In this work we have synthesized and studied, at molecular and supramolecular levels, four pentadecapeptides obtained by switching the X and Z residue with leucine and/or valine. We found that the four peptides formed different supramolecular structures corresponding to specific molecular conformations. Our results show that not only the residue type but also the exact position occupied by the residue in the motif is crucial in driving the self-aggregation. The aim of this work is to provide the basis for designing elastin-derived peptides with tunable supramolecular architecture.
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Affiliation(s)
- Brigida Bochicchio
- Department of Science, University of Basilicata, Via Ateneo Lucano 10, 85100 Potenza, Italy.
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4
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Saxena R, Nanjan MJ. Elastin-like polypeptides and their applications in anticancer drug delivery systems: a review. Drug Deliv 2013; 22:156-67. [PMID: 24215207 DOI: 10.3109/10717544.2013.853210] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Elastin-like polypeptides (ELPs) are large molecular weight biopolymers. They have been widely studied as macromolecular carriers for targeted delivery of drugs. The aim of the present article is to review the available information on ELPs (including our recent investigations), their properties, drug delivery applications to tumor sites and future perspectives. This review also provides information on the use of short synthetic ELPs for making ELP-drug conjugates, for targeted delivery of anticancer drugs. In the present review we also focus on the point that short ELPs can also be used for targeting anticancer drugs to tumor sites as they behave similar to long ELPs regarding their capacity to undergo inverse temperature transition (ITT) behavior.
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Affiliation(s)
- Rubha Saxena
- TIFAC CORE HD, J.S.S. College of Pharmacy (Off Campus, JSS University, Mysore) , Ootacamund, Tamil Nadu , India
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5
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Kurzbach D, Hassouneh W, McDaniel JR, Jaumann EA, Chilkoti A, Hinderberger D. Hydration layer coupling and cooperativity in phase behavior of stimulus responsive peptide polymers. J Am Chem Soc 2013; 135:11299-308. [PMID: 23822733 PMCID: PMC4167343 DOI: 10.1021/ja4047872] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is shown that hydrophilic (backbone) and hydrophobic (side chain) hydration layers of elastin-like polypeptides (ELPs), a class of stimulus responsive peptide polymers that exhibit lower critical solution temperature (LCST) phase transition behavior, can exist in a coupled and decoupled state. The decoupled hydration state consists of hydrophobic and hydrophilic hydration layers that respond independently to temperature, while the coupled hydration state is characterized by a common, cooperative dehydration of both hydration layers. It is further shown that the primary sequence of an ELP can be tuned to exhibit either of the hydration layer coupling modes. Charged side chains lead to decoupling, while strongly hydrophobic side chains trigger stronger interaction between hydrophilic and hydrophobic hydration, leading to coupling of both layers. Further, for aprotic residues this coupling is fostered by decreasing bulkiness of hydrophobic side chains due to larger hydration numbers and water molecules mediating coupling between side chain and backbone hydration shells. For coupled hydration shells, the LCST phase transition characterized by spin probing continuous wave electron paramagnetic resonance spectroscopy is reminiscent of a first-order process even on nanoscopic length scales. In contrast, analogous synthetic polymers exhibit nanoscale phase transitions over a broad temperature range, indicating that their nanoscale phase behavior is not of first order. Hence, our results indicate that ELPs are the first identified class of polymers that exhibit a first-order inverse phase transition on nanoscopic length scales. These results may also provide insights into the role of hydration layers in governing the structure-function relationship of intrinsically disordered proteins.
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Affiliation(s)
- Dennis Kurzbach
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Wafa Hassouneh
- Department of Biomedical Engineering, Duke University, 136 Hudson Hall, Box 90281, Durham, NC 27708-0281, USA
| | - Jonathan R. McDaniel
- Department of Biomedical Engineering, Duke University, 136 Hudson Hall, Box 90281, Durham, NC 27708-0281, USA
| | - Eva A. Jaumann
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Ashutosh Chilkoti
- Department of Biomedical Engineering, Duke University, 136 Hudson Hall, Box 90281, Durham, NC 27708-0281, USA
| | - Dariush Hinderberger
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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6
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Gronau G, Krishnaji ST, Kinahan ME, Giesa T, Wong JY, Kaplan DL, Buehler MJ. A review of combined experimental and computational procedures for assessing biopolymer structure-process-property relationships. Biomaterials 2012; 33:8240-55. [PMID: 22938765 DOI: 10.1016/j.biomaterials.2012.06.054] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 06/22/2012] [Indexed: 02/08/2023]
Abstract
Tailored biomaterials with tunable functional properties are desirable for many applications ranging from drug delivery to regenerative medicine. To improve the predictability of biopolymer materials functionality, multiple design parameters need to be considered, along with appropriate models. In this article we review the state of the art of synthesis and processing related to the design of biopolymers, with an emphasis on the integration of bottom-up computational modeling in the design process. We consider three prominent examples of well-studied biopolymer materials - elastin, silk, and collagen - and assess their hierarchical structure, intriguing functional properties and categorize existing approaches to study these materials. We find that an integrated design approach in which both experiments and computational modeling are used has rarely been applied for these materials due to difficulties in relating insights gained on different length- and time-scales. In this context, multiscale engineering offers a powerful means to accelerate the biomaterials design process for the development of tailored materials that suit the needs posed by the various applications. The combined use of experimental and computational tools has a very broad applicability not only in the field of biopolymers, but can be exploited to tailor the properties of other polymers and composite materials in general.
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Affiliation(s)
- Greta Gronau
- Laboratory for Atomistic and Molecular Mechanics, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Mass. Ave., Cambridge, MA 02139, USA
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7
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Bochicchio B, Pepe A. Role of polyproline II conformation in human tropoelastin structure. Chirality 2012; 23:694-702. [PMID: 22135799 DOI: 10.1002/chir.20979] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In this review, we present a comprehensive overview of the molecular studies on human tropoelastin domains accomplished by Tamburro and co-workers in the last decade. The used approach is the reductionist approach applied to human tropoelastin and is based on the observation that the tropoelastin gene exhibits a cassette-like organization, with a regular alternation of cross-linking and hydrophobic domains putatively responsible for the elasticity of the protein. The peculiar structure of human tropoelastin gene prompted us to study the isolated domains encoded by the exons of tropoelastin, with the perspective to get deep insights into the structural properties of the whole protein. At the molecular level, the results clearly evidence large flexibility of the polypeptide chains in the hydrophobic domains, which oscillate between rather extended and folded conformations. An important role was assigned to poly-proline II conformation considered as the hinge structure in the dynamic conformational equilibrium suggested for the hydrophobic domains. For the lysine-rich cross-linking domains, the structural studies exactly localized α-helix along the polypeptide sequence. Furthermore, at supramolecular level, these studies showed that several domains are able to self-assemble in two different aggregation patterns, the fibrous elastin-like structure for some proline-rich hydrophobic domains and the amyloid-like for some glycine-rich hydrophobic domains. Accordingly, the studies suggest that the reductionist approach was a valid tool for studying a complex protein, such as elastin, elucidating not only the structure but also the specific role played by its constituent domains.
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Affiliation(s)
- Brigida Bochicchio
- Laboratory of Protein Chemistry, Department of Chemistry A. M. Tamburro, University of Basilicata, Potenza, Italy.
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8
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Muiznieks LD, Weiss AS, Keeley FW. Structural disorder and dynamics of elastin. Biochem Cell Biol 2010; 88:239-50. [PMID: 20453927 DOI: 10.1139/o09-161] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Elastin is a self-assembling, extracellular-matrix protein that is the major provider of tissue elasticity. Here we review structural studies of elastin from over four decades, and draw together evidence for solution flexibility and conformational disorder that is inherent in all levels of structural organization. The characterization of disorder is consistent with an entropy-driven mechanism of elastic recoil. We conclude that conformational disorder is a constitutive feature of elastin structure and function.
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Affiliation(s)
- Lisa D Muiznieks
- Research Institute, Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada.
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9
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Abstract
We investigated the flexibility of full-length tropoelastin in solution by using far- and near-ultraviolet circular dichroism (UV CD) and fluorescence spectroscopy to probe for structural flexibility and residue mobility within secondary and tertiary features of the monomer. Fluorescence spectroscopy revealed the presence of exposed hydrophobicity through the binding of the hydrophobic probe 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonate (bis-ANS), which demonstrates that hydrophobic regions form clusters and are not confined to a molecular core. Near-UV CD indicated substantial mobility of aromatic residues. Structural prediction programs (PONDR, DisEMBL, and Globplot version 2.0) estimated 75 +/- 2% disorder in the tertiary structure of tropoelastin on the basis of primary sequence information. A single-site substitution of Trp for Gln (Q513W) at the tropoelastin domain 25-26 interface facilitated fluorescence spectroscopy for revealing that this region is exposed to solvent. Polarization anisotropy demonstrated substantial flexibility of W513 and little change upon denaturation of the monomer with guanidine hydrochloride. Comparable movement was found for native sequence aromatic residues in the presence of glycosaminoglycans and trifluoroethanol. These data prove the intrinsic flexibility of specific residues and adjacent sequences in any native conformation(s) they may take. This study is the first characterization of the level of mobility in defined regions of the full-length tropoelastin monomer and provides direct evidence for regions of flexible structure in tropoelastin.
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Affiliation(s)
- Lisa D Muiznieks
- School of Molecular and Microbial Biosciences, The University of Sydney, Sydney, Australia 2006
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10
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Bochicchio B, Jimenez-Oronoz F, Pepe A, Blanco M, Sandberg LB, Tamburro AM. Synthesis of and Structural Studies on Repeating Sequences of Abductin. Macromol Biosci 2005; 5:502-11. [PMID: 15948227 DOI: 10.1002/mabi.200500007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Little data exist on the structure and function of compressible elastomeric proteins such as abductin. An understanding of the underlying structural features of these proteins may lead to the development of a new class of highly tailored "compressible" hydrogels. To that effect, in this work, the structure of abductin was investigated by means of studies on several synthetic peptides corresponding to the most frequent sequences of abductin. In particular, the 10 amino acid abductin peptide sequence FGGMGGGNAG, tandem repeated in the protein, and two related 25 and 40 amino acid polypeptides were synthesized. These peptides were studied with regard to secondary structure, self-assembly, and polymer morphology. The results obtained with these peptides allow us to propose a preliminary structure-elasticity relationship for abductin not dissimilar from that currently accepted for elastin.A possible mechanism of elasticity relating abductin to elastin.
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Affiliation(s)
- Brigida Bochicchio
- Dipartimento di Chimica, Università degli Studi della Basilicata, Via Nazario Sauro 85, 85100 Potenza, Italy
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11
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Yao XL, Hong M. Structure Distribution in an Elastin-Mimetic Peptide (VPGVG)3 Investigated by Solid-State NMR. J Am Chem Soc 2004; 126:4199-210. [PMID: 15053609 DOI: 10.1021/ja036686n] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Elastin is an extracellular-matrix protein that imparts elasticity to tissues. We have used solid-state NMR to determine a number of distances and torsion angles in an elastin-mimetic peptide, (VPGVG)3, to understand the structural basis of elasticity. C-H and C-N distances between the V6 carbonyl and the V9 amide segment were measured using 13C-15N and 13C-1H rotational-echo double-resonance experiments. The results indicate the coexistence of two types of intramolecular distances: a third of the molecules have short C-H and C-N distances of 3.3 +/- 0.2 and 4.3 +/- 0.2 A, respectively, while the rest have longer distances of about 7 A. Complementing the distance constraints, we measured the (phi, psi ) torsion angles of the central pentameric unit using dipolar correlation NMR. The -angles of P7 and G8 are predominantly ~150, thus restricting the majority of the peptide to be extended. Combining all torsion angles measured for the five residues, the G8 C chemical shift, and the V6-V9 distances, we obtained a bimodal structure distribution for the PG residues in VPGVG. The minor form is a compact structure with a V6-V9 C=O-HN hydrogen bond and can be either a type II -turn or a previously unidentified turn with Pro (phi = -70, psi= 20 +/- 20) and Gly ( phi= -100 +/- 20, psi = -20 +/- 20). The major form is an extended and distorted beta-strand without a V6-V9 hydrogen bond and differs from the ideal parallel and antiparallel beta-strands. The other three residues in the VPGVG unit mainly adopt antiparallel beta-sheet torsion angles. Since (VPGVG)3 has the same 13C and 15N isotropic and anisotropic chemical shifts as the elastin-mimetic protein (VPGXG)n (X = V and K, n = 195), the observed conformational distribution around Pro and Gly sheds light on the molecular mechanism of elastin elasticity.
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Affiliation(s)
- X L Yao
- Department of Chemistry, Iowa State University, Ames, Iowa, USA
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12
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Li B, Daggett V. Molecular basis for the extensibility of elastin. MECHANICS OF ELASTIC BIOMOLECULES 2003:561-573. [DOI: 10.1007/978-94-010-0147-2_15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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13
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Abstract
Elastin, the protein responsible for the elastic properties of vertebrate tissues, has been thought to be solely restricted to that role. As a consequence, elastin was conventionally described as an amorphous polymer. Recent results in the biomedical, biochemical and biophysical fields have lead to the conclusion that the presence of elastin in the extracellular space has very complex implications involving many other molecules. The present review describes the current state of knowledge concerning elastin as an elastic macromolecule. First, the genetic, biological, biochemical and biophysical processes leading to a functional polymer are described. Second, the elastic function of elastin is discussed. The controversy on elastin structure and elasticity is discussed and a novel dynamic mechanism of elasticity proposed. Finally, pathologies where the elastin molecule is involved are considered. This updated description of functional elastin provides the required background for the understanding of its pathologies and defines clearly the properties a substance should possess to be qualified as a good elastic biomaterial.
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Affiliation(s)
- L Debelle
- Department of Chemistry, University of Basilicata, Potenza, Italy
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14
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Martino M, Bavoso A, Saviano M, Di Blasio B, Tamburro AM. Structure and dynamics of elastin building blocks. Boc-LG-OEt, Boc-VGG-OH. J Biomol Struct Dyn 1998; 15:861-75. [PMID: 9619509 DOI: 10.1080/07391102.1998.10508208] [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: 02/07/2023]
Abstract
Short di- and tripeptides such as Boc-LG-OEt, Boc-VG-OEt and Boc-VGG-OH, corresponding to abundant repetitive sequences in elastin, have been extensively studied both in solid state, by X-ray diffraction, and in solution by circular dicroism and nuclear magnetic resonance. Furthermore, theoretical procedures such as simulated annealing and molecular dynamics were also performed on these peptides. In general, the results indicate that no one single structure (be folded or extended) could be representative for these sequences in the protein, but rather that a multiplicity of interconverting conformers, ranging from folded to extended structures, should be considered. In any case, these structures, e.g. beta-turns, polyglycine II and beta-conformations, are those previously suggested to participate to conformational equilibria of elastin.
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Affiliation(s)
- M Martino
- Department of Chemistry, University of Basilicata, Potenza, Italy
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15
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Abstract
The swelling and viscoelastic properties of purified elastin were studied in aqueous solutions of superswelling agents or osmotic deswelling agents to develop models to study the behavior of elastin at frequencies not easily accessible by direct measurement. Increasing the concentration of any of the deswelling solutes (glucose, sucrose, sodium chloride, ammonium sulphate, dextran, and polyethylene glycol) increased the tensile storage and loss moduli. The viscoelastic behavior was independent of solute when compared on the basis of swelling behavior. The data collected at various solute concentrations at 37 degrees C could be reduced to one master curve, and the master curves for elastin in each of the deswelling solutes were themselves superposable. The ability to reduce the data indicates that dehydration can be used to model elastin's viscoelastic behavior at high frequencies or over short times. The viscoelastic behavior of elastin in the superswelling agents [potassium thiocyanate (KSCN), dimethyl sulfoxide (DMSO), and ethylene glycol (EG)] depended on the solute and was independent of swelling behavior. In KSCN the behavior of elastin seemed to be a continuation of the pattern established by the deswelling agents in that an increase in swelling was accompanied by a decrease in both moduli, and the viscoelastic spectra were reducible to one master curve. In high concentrations of DMSO and EG the spectra were not reducible. KSCN appears a suitable superswelling solute to model elastin's viscoelastic behavior at low frequencies or over long times.
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Affiliation(s)
- M A Lillie
- Department of Zoology, University of British Columbia, Vancouver, Canada
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16
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Broch H, Moulabbi M, Vasilescu D, Tamburro AM. Conformational and electrostatic properties of V-G-G-V-G, a typical sequence of the glycine-rich regions of elastin. An ab initio quantum molecular study. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1996; 47:394-404. [PMID: 8791163 DOI: 10.1111/j.1399-3011.1996.tb01089.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The conformational analysis and electrostatic properties of the monomeric sequence V-G-G-V-G of the glycine-rich regions of elastin is presented with the aim of explaining NMR and CD experimental results. On the basis of the molecular model NH+3-V-G-G-V-G-COO, Gaussian 92 quantum-molecular computations were performed by using principally an ab initio method at the 3-21G level and AM1. The occurrence of local secondary structures and of beta I, beta II, beta II' and VIa turns is discussed. Our results clearly demonstrate that the transconformations beta I-->half turn (which was invoked to explain experimental results) and beta I-->beta II' are theoretically allowed.
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Affiliation(s)
- H Broch
- Laboratory of Biophysics, University of Nice, Sophia Antipolis, France
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17
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Castiglione-Morelli MA, Guantieri V, Villani V, Kyriacou CP, Costa R, Tamburro AM. Conformational study of the Thr-Gly repeat in the Drosophila clock protein, PERIOD. Proc Biol Sci 1995; 260:155-63. [PMID: 7784433 DOI: 10.1098/rspb.1995.0073] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Recent results with the Drosophila melanogaster period gene suggest that the apparently conserved repetitive motif (Thr-Gly)n encoded by this gene may play an important role in the temperature compensation of the circadian clock. We have therefore initiated both a theoretical and experimental conformational analysis of (Thr-Gly)n peptides. By using a build-up method, it is clear that the hexapeptide (Thr-Gly)3 represents a 'conformational monomer' and generates a stable type II or type III beta-turn. Circular dichroism and nuclear magnetic resonance spectra of synthetic (Thr-Gly)3 and poly(Thr-Gly) peptides revealed that these peptides exhibit flexible conformations, especially in more polar environments and at higher temperatures. We speculate that this flexibility may illuminate our understanding of both the molecular mechanism of temperature compensation and the systematic geographical distribution within Europe of the Thr-Gly length polymorphism in D. melanogaster.
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18
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Abstract
Autoclaving is a standard way of purifying arterial elastin for mechanical testing, but recent evidence suggests that heating native elastin might affect its mechanical behavior. We therefore examined the quasi-static tensile properties of pig arterial tissue to see if the mechanical properties of native elastin are altered by autoclaving. From an analysis of the shapes of the stress-extension ratio curves of tissues before and after 8 h of autoclaving, we determined that the mechanical characteristics of elastin dominated the behavior of unautoclaved arterial tissue at wall stresses around 25+/-5 kPa. Autoclaving did not change the tangential modulus of the tissue at this wall stress (+/-4% 95% CI), indicating that elastin can be heated during purification without affecting its mechanical behavior. Autoclaved tissue was tested daily to determine the effects of prolonged heating of autoclaved elastin. Between tests the elastin was incubated at either 80 degrees C (experimental group) or 37 degrees C (control group). After 6 days the average modulus of the control group was unchanged from the initial value, while the average modulus of the experimental group was 7%+/-2% (95% CI) lower. At shorter times the modulus of the experimental group was not significantly reduced. The slight decrease in modulus suggests a slow chemical degradation may occur with prolonged heating, but its time course and magnitude are such that it would not affect standard mechanical tests.
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Affiliation(s)
- M A Lillie
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
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19
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On the Molecular and Supramolecular Structure of Elastin. TOPICS IN MOLECULAR ORGANIZATION AND ENGINEERING 1994. [DOI: 10.1007/978-94-011-0822-5_36] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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20
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Villani V, Tamburro AM. Conformational analysis by molecular mechanics energy minimizations of the tetrapeptide Boc-Gly-Leu-Gly-Gly–NMe, a recurring sequence of elastin. ACTA ACUST UNITED AC 1993. [DOI: 10.1039/p29930001951] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Tamburro AM, Guantieri V, Gordini DD. Synthesis and structural studies of a pentapeptide sequence of elastin. Poly (Val-Gly-Gly-Leu-Gly). J Biomol Struct Dyn 1992; 10:441-54. [PMID: 1492919 DOI: 10.1080/07391102.1992.10508661] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Poly (Val-Gly-Gly-Leu-Gly), a polypeptide mimicking the physico-chemical properties of the glycine-rich regions of elastin, has been synthesized and studied both in solution and in the aggregated state. By comparison, also the conformation of different "monomeric" units has been investigated. The polymer showed increased disorder with respect to the "monomers", the molecular conformation being accounted for by a more or less random collection of isolated beta-turns. Nevertheless, in the solid state the polymer is able to adopt supramolecular structures reminiscent of those found for elastin.
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Affiliation(s)
- A M Tamburro
- Dept. of Chemistry, Università della Basilicata, Potenza, Italy
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Tamburro AM, Guantieri V, Scopa A, Drabble JM. Polypeptide models of elastin: CD and NMR studies on synthetic poly(X-Gly-Gly). Chirality 1991; 3:318-23. [PMID: 1742165 DOI: 10.1002/chir.530030417] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Poly(X-Gly-Gly), simple structural models for the hydrophobic, proline-devoid, regions of elastin, have been synthesized and studied by circular dichroism and NMR spectroscopies. The results gave evidence of type II beta-turns as the only ordered structure present in the polymers. The stability of the turns has been shown to decrease on hydration and to increase in the series Leu less than Ala less than Val less than Ile.
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Affiliation(s)
- A M Tamburro
- Department of Chemistry, University of Basilicata, Potenza, Italy
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