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Aggarwal N, Eliaz D, Cohen H, Rosenhek-Goldian I, Cohen SR, Kozell A, Mason TO, Shimanovich U. Protein nanofibril design via manipulation of hydrogen bonds. Commun Chem 2021; 4:62. [PMID: 36697777 PMCID: PMC9814780 DOI: 10.1038/s42004-021-00494-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 03/16/2021] [Indexed: 02/03/2023] Open
Abstract
The process of amyloid nanofibril formation has broad implications including the generation of the strongest natural materials, namely silk fibers, and their major contribution to the progression of many degenerative diseases. The key question that remains unanswered is whether the amyloidogenic nature, which includes the characteristic H-bonded β-sheet structure and physical characteristics of protein assemblies, can be modified via controlled intervention of the molecular interactions. Here we show that tailored changes in molecular interactions, specifically in the H-bonded network, do not affect the nature of amyloidogenic fibrillation, and even have minimal effect on the initial nucleation events of self-assembly. However, they do trigger changes in networks at a higher hierarchical level, namely enhanced 2D packaging which is rationalized by the 3D hierarchy of β-sheet assembly, leading to variations in fibril morphology, structural composition and, remarkably, nanomechanical properties. These results pave the way to a better understanding of the role of molecular interactions in sculpting the structural and physical properties of protein supramolecular constructs.
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Affiliation(s)
- Nidhi Aggarwal
- grid.13992.300000 0004 0604 7563Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, Israel
| | - Dror Eliaz
- grid.13992.300000 0004 0604 7563Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, Israel
| | - Hagai Cohen
- grid.13992.300000 0004 0604 7563Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Irit Rosenhek-Goldian
- grid.13992.300000 0004 0604 7563Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Sidney R. Cohen
- grid.13992.300000 0004 0604 7563Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Anna Kozell
- grid.13992.300000 0004 0604 7563Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, Israel
| | - Thomas O. Mason
- grid.13992.300000 0004 0604 7563Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, Israel
| | - Ulyana Shimanovich
- grid.13992.300000 0004 0604 7563Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, Israel
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2
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Sambasivam D, Sivanesan S, Sultana S, Rajadas J. Conformational Preferences of Aβ25-35 and Aβ35-25 in Membrane Mimicking Environments. Protein Pept Lett 2019; 26:386-390. [PMID: 30836907 DOI: 10.2174/0929866526666190228122849] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 01/03/2019] [Accepted: 02/04/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND The structural transition of aggregating Abeta peptides is the key event in the progression of Alzheimer's Disease (AD). OBJECTIVE In the present work, the structural modifications of toxic Aβ25-35 and the scrambled Aβ35-25 were studied in Trifluoroethanol (TFE) and in aqueous SDS micelles. METHODS Using CD spectroscopic investigations, the conformational transition of Aβ25-35 and Aβ35-25 peptides were determined in different membrane mimicking environments such as TFE and SDS. An interval scan CD of the peptides on evaporation of TFE was performed. TFE titrations were carried out to investigate the intrinsic ability of the structural conformations of peptides. RESULTS We show by spectroscopic evidence that Aβ25-35 prefers beta sheet structures upon increasing TFE concentrations. On the other hand, the non-toxic scrambled Aβ35-25 peptide only undergoes a transition from random coil to α-helix conformation with increasing TFE. In the interval scan studies, Aβ25-35 did not show any structural transitions, whereas Aβ35-25 showed transition from α-helix to β-sheet conformation. In membrane simulating aqueous SDS micelles, Aβ25-35 showed a transition from random coil to α-helix while Aβ35-25 underwent transition from random coil to β-sheet conformation. CONCLUSION Overall, the current results seek new insights into the structural properties of amyloidogenic and the truncated sequence in membrane mimicking solvents.
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Affiliation(s)
- Dhandayuthapani Sambasivam
- Bioorganic Chemistry Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India.,Department of Chemistry, St Peter's Institute of Higher Education and Research, Chennai-600054, India
| | - Senthilkumar Sivanesan
- Bioorganic Chemistry Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India
| | - Sayeeda Sultana
- Department of Chemistry, St Peter's Institute of Higher Education and Research, Chennai-600054, India
| | - Jayakumar Rajadas
- Bioorganic Chemistry Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India.,Biomaterials and Advanced Drug Delivery Laboratory (BioADD), Stanford University School of Medicine, Stanford, CA, United States
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3
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Use-dependent inhibition of glycine-activated chloride current in rat neurons by β-amyloid peptide pretreated with hexafluoroisopropanol. Neuroreport 2017; 28:579-583. [PMID: 28489663 DOI: 10.1097/wnr.0000000000000801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Hexafluoroisopropanol (HFIP) is a nonpolar organic solvent that is often used to prepare β-amyloid peptide (Aβ) samples. In this work, we compare the effects of two different species derived from synthetic Aβ1-42 and prepared without HFIP (Aβ) or using HFIP (Aβ/HFIP) on the glycine-activated chloride current (IGly). The experiments were conducted on the pyramidal neurons isolated from CA3 region of rat hippocampus. Transmembrane currents were recorded using a conventional patch-clamp technique in the whole-cell configuration. The IGly was induced by a step application of the agonist for 600 ms through glass capillary. Aβ or Aβ/HFIP was coapplied with glycine. The effects of the two species of the peptide have similar and distinctive features. Both substances caused a reduction in the peak amplitude and an acceleration of desensitization of the IGly. At the same time, the effect of Aβ/HFIP was found to develop and recover more slowly and required several repeated applications for its saturation (use dependence). The effect of Aβ/HFIP was voltage independent and equally pronounced at negative and positive membrane potentials. First, our results confirm that HFIP pretreatment may influence the properties of Aβ. Second, new information on the glycine receptor ability to interact with drugs in use-dependent mode was obtained.
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Khatua P, Jose JC, Sengupta N, Bandyopadhyay S. Conformational features of the Aβ42 peptide monomer and its interaction with the surrounding solvent. Phys Chem Chem Phys 2016; 18:30144-30159. [DOI: 10.1039/c6cp04925g] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Heterogeneous conformational flexibility of the Aβ monomers has been found to be correlated with the corresponding non-uniform entropy gains.
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Affiliation(s)
- Prabir Khatua
- Molecular Modeling Laboratory
- Department of Chemistry
- Indian Institute of Technology
- Kharagpur-721302
- India
| | - Jaya C. Jose
- Physical Chemistry Division
- CSIR-National Chemical Laboratory
- Pune 411008
- India
| | - Neelanjana Sengupta
- Department of Biological Sciences
- Indian Institute of Science Education and Research Kolkata
- Mohanpur-741246
- India
| | - Sanjoy Bandyopadhyay
- Molecular Modeling Laboratory
- Department of Chemistry
- Indian Institute of Technology
- Kharagpur-721302
- India
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5
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Błaszak M, Jankowska E, Kowalik-Jankowska T. Copper(II) complexes of neuropeptide gamma mutant (H4A) products of metal-catalyzed oxidation. Polyhedron 2014. [DOI: 10.1016/j.poly.2013.11.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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6
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Amyloid-Like Fibril Formation by Tachykinin Neuropeptides and Its Relevance to Amyloid β-Protein Aggregation and Toxicity. Cell Biochem Biophys 2012; 64:29-44. [DOI: 10.1007/s12013-012-9364-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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7
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Shanmugam G, Polavarapu PL, Láng E, Majer Z. Conformational analysis of amyloid precursor protein fragment containing amino acids 667–676, and the effect of d-Asp and iso-Asp substitution at Asp672 residue. J Struct Biol 2012; 177:621-9. [DOI: 10.1016/j.jsb.2012.01.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2011] [Revised: 01/10/2012] [Accepted: 01/26/2012] [Indexed: 11/28/2022]
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8
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Pietruszka M, Jankowska E, Kowalik-Jankowska T, Szewczuk Z, Smużyńska M. Complexation Abilities of Neuropeptide Gamma toward Copper(II) Ions and Products of Metal-Catalyzed Oxidation. Inorg Chem 2011; 50:7489-99. [DOI: 10.1021/ic2002942] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marta Pietruszka
- Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wroclaw, Poland
| | - Elżbieta Jankowska
- Faculty of Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk, Poland
| | | | - Zbigniew Szewczuk
- Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wroclaw, Poland
| | - Maria Smużyńska
- Faculty of Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk, Poland
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Koivisto JJ, Kumpulainen ETT, Koskinen AMP. Conformational ensembles of flexible beta-turn mimetics in DMSO-d6. Org Biomol Chem 2010; 8:2103-16. [PMID: 20401387 DOI: 10.1039/b921794k] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Beta-turns play an important role in peptide and protein chemistry, biophysics, and bioinformatics. The aim of this research was to study short linear peptides that have a high propensity to form beta-turn structures in solution. In particular, we examined conformational ensembles of beta-turn forming peptides with a general sequence CBz-L-Ala-L-Xaa-Gly-L-Ala-OtBu. These tetrapeptides, APGA, A(4R)MePGA, and A(4S)MePGA, incorporate proline, (4R)-methylproline, and (4S)-methylproline, respectively, at the Xaa position. To determine the influence of the 4-methyl substituted prolines on the beta-turn populations, the NAMFIS (NMR analysis of molecular flexibility in solution) deconvolution analysis for these three peptides were performed in DMSO-d(6) solution. The NBO (natural bond orbital) method was employed to gain further insight into the results obtained from the NAMFIS analysis. The emphasis in the NBO analysis was to characterize remote intramolecular interactions that could influence the backbone-backbone interactions contributing to beta-turn stability. NAMFIS results indicate that the enantiospecific incorporation of the methyl substituent at the C(gamma) (C4) position of the proline residue can be used to selectively control the pyrrolidine ring puckering propensities and, consequently, the preferred varphi,psi angles associated with the proline residue in beta-turn forming peptides. The NAMFIS analyses show that the presence of (4S)-methylproline in A(4S)MePGA considerably increased the type II beta-turn population with respect to APGA and A(4R)MePGA. The NBO calculations suggest that this observation can be rationalized based on an n-->pi* interaction between the N-terminus alanine carbonyl oxygen and the proline carbonyl group. Several other interactions between remote orbitals in these peptides provide a more detailed explanation for the observed population distributions.
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Affiliation(s)
- Jari J Koivisto
- Aalto University School of Science and Technology, Faculty of Chemistry and Materials Sciences, Department of Chemistry, P.O.Box 16100, FI-00076 Aalto, Finland
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Liu K, Castillo MD, Murthy RG, Patel N, Rameshwar P. Tachykinins and Hematopoiesis. Clin Chim Acta 2007; 385:28-34. [PMID: 17698052 DOI: 10.1016/j.cca.2007.07.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Revised: 07/03/2007] [Accepted: 07/05/2007] [Indexed: 10/23/2022]
Abstract
Originally discovered in the 1930s, tachykinins have been a subject of renewed interest. Antagonists to the tachykinin receptors have shown potential in the treatment of a variety of maladies including neurodegenerative disorders, heart disease, pain perception and malignancies. Tachykinins have been the subject of intense studies due to their impact on hematopoiesis that has significant effects on endothelial tissue and vascular conditions. Hematopoiesis relies on a relatively small subset of bone marrow-resident hematopoietic stem cells. This review discusses the network developed by cytokines and the tachykinins to regulate hematopoiesis. An understanding of tachykinin effect on normal hematopoietic functions and their involvement in hematological disorders could lead to new treatments for bone marrow disorders such as fibrosis, leukemia and anemia.
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Affiliation(s)
- Katherine Liu
- Graduate School of Biomedical Sciences, UMDNJ, Newark, NJ 07103, USA
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Willis M, Hutter-Paier B, Wietzorrek G, Windisch M, Humpel C, Knaus HG, Marksteiner J. Localization and expression of substance P in transgenic mice overexpressing human APP751 with the London (V717I) and Swedish (K670M/N671L) mutations. Brain Res 2007; 1143:199-207. [PMID: 17328871 DOI: 10.1016/j.brainres.2007.01.080] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Revised: 01/16/2007] [Accepted: 01/18/2007] [Indexed: 10/23/2022]
Abstract
Substance P-like immunoreactivity (-LI) is found in neuritic plaques, and is reduced in patients suffering from Alzheimer disease (AD). In this study, we examined the distribution and expression of substance P in transgenic mice overexpressing human amyloid precursor protein (hAPP) APP751 with the London (V717I) and Swedish (K670M/N671L) mutations. Immunohistochemistry was performed to localize substance P- and glial fibrillary acidic protein-LI by confocal microscopy. In hAPP transgenic mice, the number of beta-amyloid plaques significantly increased from 6 to 12 months. About 5% of beta-amyloid plaques were substance P-immunoreactive. In transgenic mice, the morphology of substance P-immunoreactive structures changed by consisting of swollen and dystrophic neurites mostly associated with beta-amyloid plaques. The overall localization and the relative substance P densities were not different between wild type and transgenic mice at 6 and 12 months. At month 12, a dramatic change in the distribution pattern of substance P-LI was observed as it was now expressed in a high number of reactive astrocytes. This expression of substance P in astrocytes was mainly found in the hippocampal formation and thalamic nuclei with a preferential association with beta-amyloid plaques, whereas in cortical regions only faintly substance P-immunoreactive astrocytes were observed. This study indicates that substance P undergoes complex changes in this animal Alzheimer disease model. Future experiments including substance P antagonists are necessary to further explore the interaction between beta-amyloid deposits and substance P.
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Affiliation(s)
- Michael Willis
- Department of General Psychiatry, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck, Austria
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12
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Abstract
The free energy landscape for folding of the Alzheimer's amyloid-beta(25-35) peptide is explored using replica exchange molecular dynamics in both pure water and in HFIP/water cosolvent. This amphiphilic peptide is a natural by-product of the Alzheimer's amyloid-beta(1-40) peptide and retains the toxicity of its full-length counterpart as well as the ability to aggregate into beta-sheet-rich fibrils. Our simulations reveal that the peptide preferentially populates a helical structure in apolar organic solvent, while in pure water, the peptide adopts collapsed coil conformations and to a lesser extent beta-hairpin conformations. The beta-hairpin is characterized by a type II' beta-turn involving residues G29 and A30 and two short beta-strands involving residues N27, K28, I31, and I32. The hairpin is stabilized by backbone hydrogen-bonding interactions between residues K28 and I31; S26 and G33; and by side-chain-to-side-chain interactions between N27 and I32. Implications regarding the mechanism of aggregation of this peptide into fibrils and the role of the environment in modulating secondary structure are discussed.
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Affiliation(s)
- Guanghong Wei
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California, USA
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13
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Shanmugam G, Polavarapu PL, Gopinath D, Jayakumar R. The structure of antimicrobial pexiganan peptide in solution probed by Fourier transform infrared absorption, vibrational circular dichroism, and electronic circular dichroism spectroscopy. Biopolymers 2005; 80:636-42. [PMID: 15657879 DOI: 10.1002/bip.20132] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Pexiganan (Gly-Ile-Gly-Lys-Phe-Leu-Lys-Lys-Ala-Lys-Lys-Phe-Gly-Lys-Ala-Phe-Val-Lys-Ile-Leu-Lys-Lys), a 22 amino acid peptide, is an analogue of the magainin family of antimicrobial peptides present in the skin of the African clawed frog. Conformational analysis of pexiganan was carried out in different solvent environments for the first time. Organic solvents, trifluoroethanol (TFE) and methanol, were used to study the secondary structural preferences of this peptide in the membrane-mimicking environments. In addition, aqueous (D2O) and dimethyl sulfoxide (DMSO) solutions were also investigated to study the role of hydrogen bonding involved in the secondary structure formation. Fourier transform infrared absorption, vibrational circular dichroism (VCD), and electronic circular dichroism (ECD) measurements were carried out under the same conditions to ascertain the conformational assignments in different solvents. All these spectroscopic measurements suggest that the pexiganan peptide has the tendency to adopt different structures in different environments. Pexiganan appears to adopt an alpha-helical conformation in TFE, a sheet-stabilized beta-turn structure in methanol, a random coil with beta-turn structure in D2O, and a solvated beta-turn structure in DMSO.
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Affiliation(s)
- Ganesh Shanmugam
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA
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14
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Abstract
The fragment A beta(25-35) of the Alzheimer's amyloid beta-peptide, like its full-length peptide A beta(1-42), has shown neurotoxic activities in cultured cells. The conformational preference of this important peptide is examined here in solution, gel, and film states (obtained with organic and aqueous solvents) by vibrational circular dichroism spectroscopy for the first time. For comparative studies, vibrational absorption and electronic circular dichroism measurements were also carried out under identical conditions. The peptide was found to adopt beta-sheet and beta-turn structures, with their relative proportions changing in different environments.
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Affiliation(s)
- Ganesh Shanmugam
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA
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15
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Shanmugam G, Jayakumar R. Structural analysis of amyloid ? peptide fragment (25-35) in different microenvironments. Biopolymers 2004; 76:421-34. [PMID: 15468066 DOI: 10.1002/bip.20131] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Amyloid beta (Abeta) peptides are one of the classes of amphiphilic molecules that on dissolution in aqueous solvents undergo interesting conformational transitions. These conformational changes are known to be associated with their neuronal toxicity. The mechanism of structural transition involved in the monomeric Abeta to toxic assemblage is yet to be understood at the molecular level. Early results indicate that oriented molecular crowding has a profound effect on their assemblage formation. In this work, we have studied how different microenvironments affect the conformational transitions of one of the active amyloid beta-peptide fragments (Abeta(25-35)). Spectroscopic techniques such as CD and Fourier transform infrared spectroscopy were used. It was observed that a stored peptide concentrates on dissolution in methanol adopts a minor alpha-helical conformation along with unordered structures. On changing the methanol concentration in the solvated film form, the conformation switches to the antiparallel beta-sheet structure on the hydrophilic surface, whereas the peptide shows transition from a mixture of helix and unordered structure into predominantly a beta-sheet with minor contribution of helix structure on the hydrophobic surface. Our present investigations indicate that the conformations induced by the different surfaces dictate the gross conformational preference of the peptide concentrate.
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Affiliation(s)
- Ganesh Shanmugam
- Bioorganic Laboratory, Central Leather Research Institute, Adyar, Chennai-600020, Tamilnadu, India
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16
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Ganesh S, Jayakumar R. Circular dichroism and Fourier transform infrared spectroscopic studies on self-assembly of tetrapeptide derivative in solution and solvated film. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2003; 61:122-8. [PMID: 12558947 DOI: 10.1034/j.1399-3011.2003.00039.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Aggregation of the hydrophobic peptide derivative Boc-Ala-Ile-Ile-Gly-OMe (1) was examined in methanol solution and in solvated film states. Formation of the peptide by self-assembly was evidenced using fluorescence [Mg salt of 8-anilino-naphthalenesulfonic acid (ANS) as an external probe] and circular dichroism (CD) spectroscopic techniques. In solution, peptide 1 formed as a stable aggregate at a concentration around 3 x 10(-4)m. The peptide gelled into a thin film for which we carried out CD and Fourier transform infrared (FTIR) measurements. Our spectroscopic study on peptide films at differing methanol concentrations indicates that the helical content of the peptide decreases with decreasing methanol concentration in solvated films. However, by reducing the methanol concentration we were able to observe a conformational transition from a predominantly helical turn to a beta-sheet structure via a random coil conformation. Our study focused on the aggregation of the alpha-helical turn-forming peptide derivative, which shows conformational transition on changing solvent concentration in the film form.
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Affiliation(s)
- S Ganesh
- Bioorganic Laboratory, Central Leather Research Institute, Chennai, India
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Abstract
Both the aqueous and the lipid-induced structure of eledoisin, an undecapeptide of mollusk origin, have been studied by two-dimensional proton nuclear magnetic resonance spectroscopy and distance geometry calculations. Unambiguous nuclear magnetic resonance assignments of protons have been made with the aid of correlation spectroscopy experiments and nuclear Overhauser effect spectroscopy experiments. The distance constraints obtained from the nuclear magnetic resonance data have been utilized in a distance geometry algorithm to generate a family of structures, which have been refined using restrained energy minimization and dynamics. These data show that, while in water and dimethyl sulfoxide, eledoisin prefers to be in an extended chain conformation, whereas in the presence of perdeuterated dodecylphosphocholine micelles, a membrane model system, helical conformation is induced in the central core and C-terminal region (K4-M11) of the peptide. N terminus, though less defined, also displays some degree of order and a possible turn structure. The conformation adopted by eledoisin in the presence of dodecylphosphocholine micelles is similar to the structural motif typical of neurokinin-2 selective agonists and with that reported for kassinin in hydrophobic environment.
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Dante S, Hauss T, Dencher NA. Beta-amyloid 25 to 35 is intercalated in anionic and zwitterionic lipid membranes to different extents. Biophys J 2002; 83:2610-6. [PMID: 12414694 PMCID: PMC1302346 DOI: 10.1016/s0006-3495(02)75271-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Neuronal plasma membranes are thought to be the primary target of the neurotoxic beta-amyloid peptides (Abeta) in the pathogenesis of the Alzheimer's disease. Histologically, Abeta peptides are observed as extracellular macroscopic senile plaques, and most biophysical techniques have indicated the presence of Abeta close to the lipid headgroup region but not in the core of the membrane bilayers. The focus of this study is an investigation of the interaction between Abeta and lipid bilayers from a structural point of view. Neutron diffraction with the use of selectively deuterated amino acids has allowed us to determine unambiguously the position of the neurotoxic fragment Abeta (25-35) in the membrane. Two populations of the peptide are detected, one in the aqueous vicinity of the membrane surface and the second inside the hydrophobic core of the lipid membrane. The location of the C terminus was studied in two different lipid compositions and was found to be dependent on the surface charge of the membrane. The localization of beta-amyloid peptides in cell membranes will offer new insights on their mechanism in the neurodegenerative process associated with Alzheimer's disease and might provide clues for therapeutic developments.
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Affiliation(s)
- Silvia Dante
- Physical Biochemistry, Darmstadt University of Technology, Petersenstrasse 22, D-64287 Darmstadt, Germany.
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Ganesh S, Jayakumar R. Role of N-t-Boc group in helix initiation in a novel tetrapeptide. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2002; 59:249-56. [PMID: 12010515 DOI: 10.1034/j.1399-3011.2002.02989.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Protecting groups in N- and C-terminal positions play a decisive role in the conformational preference of smaller peptides. Conformational analysis of tetrapeptide derivatives containing Ala, Ile and Gly residues was performed. Peptide 1, Boc-Ala-Ile-Ile-Gly-OMe (Boc: tert-butyloxycarbonyl) has a predominantly helical turn conformation in all the alcoholic solvents studied, whereas in the solid state it has a beta-sheet conformation. In contrast, peptide 2, Ac-Ala-Ile-Ile-Gly-OMe (Ac: acetyl) has a random coil conformation in solution. The FTIR spectrum of peptide 1 shows a lower frequency of urethane carbonyl, indicating involvement of the carbonyl group in hydrogen bonding in the helical turn.
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Affiliation(s)
- S Ganesh
- Bioorganic Laboratory, Central Leather Research Institute, Adyar, Chennai, India.
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