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Cera L, Gonzalez GM, Liu Q, Choi S, Chantre CO, Lee J, Gabardi R, Choi MC, Shin K, Parker KK. A bioinspired and hierarchically structured shape-memory material. NATURE MATERIALS 2021; 20:242-249. [PMID: 32868876 DOI: 10.1038/s41563-020-0789-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 07/29/2020] [Indexed: 06/11/2023]
Abstract
Shape-memory polymeric materials lack long-range molecular order that enables more controlled and efficient actuation mechanisms. Here, we develop a hierarchical structured keratin-based system that has long-range molecular order and shape-memory properties in response to hydration. We explore the metastable reconfiguration of the keratin secondary structure, the transition from α-helix to β-sheet, as an actuation mechanism to design a high-strength shape-memory material that is biocompatible and processable through fibre spinning and three-dimensional (3D) printing. We extract keratin protofibrils from animal hair and subject them to shear stress to induce their self-organization into a nematic phase, which recapitulates the native hierarchical organization of the protein. This self-assembly process can be tuned to create materials with desired anisotropic structuring and responsiveness. Our combination of bottom-up assembly and top-down manufacturing allows for the scalable fabrication of strong and hierarchically structured shape-memory fibres and 3D-printed scaffolds with potential applications in bioengineering and smart textiles.
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Affiliation(s)
- Luca Cera
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Grant M Gonzalez
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Qihan Liu
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Suji Choi
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Christophe O Chantre
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Juncheol Lee
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
| | - Rudy Gabardi
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
| | - Kwanwoo Shin
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, Seoul, Korea
| | - Kevin Kit Parker
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
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2
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Watase Y, Takahashi H, Ushio K, Fujii M, Sakai M. IR super-resolution imaging of avian feather keratins detected by using vibrational sum-frequency generation. Biophys Chem 2020; 267:106482. [PMID: 33022568 DOI: 10.1016/j.bpc.2020.106482] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 09/19/2020] [Accepted: 09/19/2020] [Indexed: 11/19/2022]
Abstract
IR super-resolution imaging of the cross section of the rachis of an avian feather was carried out by using a vibrational sum-frequency generation (VSFG) detected IR microscope with a sub-micrometer spatial resolution. In the YYX polarization combination, we clearly observed strong signals in the entire region of the rachis at the amide I vibration of β-keratin. On the other hand, the signal disappears from most of the cross section in the XXY polarization combination. Because the VSFG imaging detects the signal only from the interface, we conclude that the interfacial deflection inside of a rachis was detected.
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Affiliation(s)
- Yukihisa Watase
- Laboratory for Chemistry and Life Science, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Hirona Takahashi
- Department of Chemistry, Faculty of Science, Okayama University of Science 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan
| | - Kohei Ushio
- Laboratory for Chemistry and Life Science, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.
| | - Makoto Sakai
- Department of Chemistry, Faculty of Science, Okayama University of Science 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan.
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3
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Laurent CM, Dyke JM, Cook RB, Dyke G, de Kat R. Spectroscopy on the wing: Investigating possible differences in protein secondary structures in feather shafts of birds using Raman spectroscopy. J Struct Biol 2020; 211:107529. [PMID: 32416130 DOI: 10.1016/j.jsb.2020.107529] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/24/2020] [Accepted: 05/03/2020] [Indexed: 10/24/2022]
Abstract
The central shaft of a bird's flight feather bears most of the aerodynamic load during flight and exhibits some remarkable mechanical properties. The shaft comprises two parts, the calamus and the rachis. The calamus is at the base of the shaft, while the rachis is the longer upper part which supports the vanes. The shaft is composed of a fibrous outer cortex, and an inner foam-like core. Recent nanoindentation experiments have indicated that reduced modulus values, Er, for the inner and outer regions of the cortex can vary, with the Er values of the inner region slightly greater than those of the outer region. In this work, Raman spectroscopy is used to investigate the protein secondary structures in the inner and outer regions of the feather cortex. Analysis of the Amide I region of Raman spectra taken from four birds (Swan, Gull, Mallard and Kestrel) shows that the β-sheet structural component decreases between the inner and outer region, relative to the protein side-chain components. This finding is consistent with the proposal that Er values are greater in the inner region than the outer region. This work has shown that Raman spectroscopy can be used effectively to study the change in protein secondary structure between the inner and outer regions of a feather shaft.
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Affiliation(s)
- Christian M Laurent
- Aerodynamics and Flight Mechanics, University of Southampton, SO17 1BJ, UK; Ocean and Earth Science, National Oceanography Centre, SO17 1BJ, UK; Department of Biology and Geology, Babes-Bolyai University, Romania.
| | - John M Dyke
- School of Chemistry, University of Southampton, SO17 1BJ, UK.
| | - Richard B Cook
- nCATS National Centre for Advanced Tribology Southampton, University of Southampton, SO17 1BJ, UK
| | - Gareth Dyke
- Department of Biology and Geology, Babes-Bolyai University, Romania
| | - Roeland de Kat
- Aerodynamics and Flight Mechanics, University of Southampton, SO17 1BJ, UK; Faculty of Military Sciences, Netherlands Defence Academy, The Netherlands
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4
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Nuutinen EM, Willberg-Keyriläinen P, Virtanen T, Mija A, Kuutti L, Lantto R, Jääskeläinen AS. Green process to regenerate keratin from feathers with an aqueous deep eutectic solvent. RSC Adv 2019; 9:19720-19728. [PMID: 35519403 PMCID: PMC9065387 DOI: 10.1039/c9ra03305j] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 06/14/2019] [Indexed: 11/21/2022] Open
Abstract
In the present study, waste feathers were processed into uniform keratin feedstock using an aqueous, inexpensive and non-toxic deep eutectic solvent.
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Affiliation(s)
- Emmi-Maria Nuutinen
- Solutions for Natural Resources and Environment
- VTT
- Technical Research Centre of Finland
- Espoo
- Finland
| | - Pia Willberg-Keyriläinen
- Solutions for Natural Resources and Environment
- VTT
- Technical Research Centre of Finland
- Espoo
- Finland
| | - Tommi Virtanen
- Solutions for Natural Resources and Environment
- VTT
- Technical Research Centre of Finland
- Espoo
- Finland
| | - Alice Mija
- Université Côte d'Azur
- Université Nice-Sophia Antipolis
- Institut de Chimie de Nice
- 06108 Nice Cedex 02
- France
| | - Lauri Kuutti
- Solutions for Natural Resources and Environment
- VTT
- Technical Research Centre of Finland
- Espoo
- Finland
| | - Raija Lantto
- Solutions for Natural Resources and Environment
- VTT
- Technical Research Centre of Finland
- Espoo
- Finland
| | - Anna-Stiina Jääskeläinen
- Solutions for Natural Resources and Environment
- VTT
- Technical Research Centre of Finland
- Espoo
- Finland
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5
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Kuzuhara A. A Raman spectroscopic investigation of the mechanism of the reduction in hair with thioglycerol and the accompanying disulphide conformational changes. Int J Cosmet Sci 2017; 40:34-43. [DOI: 10.1111/ics.12429] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 09/14/2017] [Indexed: 11/29/2022]
Affiliation(s)
- A. Kuzuhara
- Department of Costume and Clothing Science; Faculty of Home Economics; Tokyo Kasei University; 1-18-1, Kaga, Itabashi-ku Tokyo 173-8602 Japan
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6
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Wang L, Nie Y, Zhang X, Zeng S, Zhang S, Zheng S. Synergistic Effects of Cosolvents on the Dissolution of Wool Keratin Using Ionic Liquids. Chem Eng Technol 2016. [DOI: 10.1002/ceat.201500646] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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7
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Shaabani A, Hezarkhani Z, Faroghi MT. Wool-SO3H and nano-Fe3O4@wool as two green and natural-based renewable catalysts in one-pot isocyanide-based multicomponent reactions. MONATSHEFTE FUR CHEMIE 2016. [DOI: 10.1007/s00706-016-1717-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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8
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Kuzuhara A. Internal structural changes in keratin fibres resulting from combined hair waving and stress relaxation treatments: a Raman spectroscopic investigation. Int J Cosmet Sci 2015; 38:201-9. [DOI: 10.1111/ics.12278] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 09/12/2015] [Indexed: 11/29/2022]
Affiliation(s)
- A. Kuzuhara
- Research and Development Department; Sunny-Place Co., Ltd.; 4-6-8 Kuramae Taito-ku Tokyo 111-0051 Japan
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9
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Mura S, Greppi G, Malfatti L, Lasio B, Sanna V, Mura ME, Marceddu S, Lugliè A. Multifunctionalization of wool fabrics through nanoparticles: A chemical route towards smart textiles. J Colloid Interface Sci 2015; 456:85-92. [DOI: 10.1016/j.jcis.2015.06.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 06/08/2015] [Accepted: 06/11/2015] [Indexed: 10/23/2022]
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10
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Kuzuhara A. Internal structure changes in bleached black human hair resulting from chemical treatments: A Raman spectroscopic investigation. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.07.075] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Ji Y, Chen J, Lv J, Li Z, Xing L, Ding S. Extraction of keratin with ionic liquids from poultry feather. Sep Purif Technol 2014. [DOI: 10.1016/j.seppur.2014.05.049] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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12
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Navarra G, Tinti A, Di Foggia M, Leone M, Militello V, Torreggiani A. Metal ions modulate thermal aggregation of beta-lactoglobulin: A joint chemical and physical characterization. J Inorg Biochem 2014; 137:64-73. [DOI: 10.1016/j.jinorgbio.2014.04.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/02/2014] [Accepted: 04/02/2014] [Indexed: 10/25/2022]
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13
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Ridgley DM, Claunch EC, Barone JR. Characterization of large amyloid fibers and tapes with Fourier transform infrared (FT-IR) and Raman spectroscopy. APPLIED SPECTROSCOPY 2013; 67:1417-1426. [PMID: 24359656 DOI: 10.1366/13-07059] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Amyloids are self-assembled protein structures implicated in a host of neurodegenerative diseases. Organisms can also produce "functional amyloids" to perpetuate life, and these materials serve as models for robust biomaterials. Amyloids are typically studied using fluorescent dyes, Fourier transform infrared (FT-IR), or Raman spectroscopy analysis of the protein amide I region, and X-ray diffraction (XRD) because the self-assembled β-sheet secondary structure of the amyloid can be easily identified with these techniques. Here, FT-IR and Raman spectroscopy analyses are described to characterize amyloid structures beyond just identification of the β-sheet structure. It has been shown that peptide mixtures can self-assemble into nanometer-sized amyloid structures that then continue to self-assemble to the micrometer scale. The resulting structures are flat tapes of low rigidity or cylinders of high rigidity depending on the peptides in the mixture. By monitoring the aggregation of peptides in solution using FT-IR spectroscopy, it is possible to identify specific amino acids implicated in β-sheet formation and higher order self-assembly. It is also possible to predict the final tape or cylinder morphology and gain insight into the structure's physical properties based on observed intermolecular interactions during the self-assembly process. Tapes and cylinders are shown to both have a similar core self-assembled β-sheet structure. Soft tapes also have weak hydrophobic interactions between alanine, isoleucine, leucine, and valine that facilitate self-assembly. Rigid cylinders have similar hydrophobic interactions that facilitate self-assembly and also have extensive hydrogen bonding between glutamines. Raman spectroscopy performed on the dried tapes and fibers shows the persistence of these interactions. The spectroscopic analyses described could be generalized to other self-assembling amyloid systems to explain property and morphological differences.
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Affiliation(s)
- Devin M Ridgley
- Biological Systems Engineering Department, Virginia Tech, 303 Seitz Hall, Blacksburg, VA 24061 USA
| | - Elizabeth C Claunch
- Biological Systems Engineering Department, Virginia Tech, 303 Seitz Hall, Blacksburg, VA 24061 USA
| | - Justin R Barone
- Biological Systems Engineering Department, Virginia Tech, 303 Seitz Hall, Blacksburg, VA 24061 USA
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14
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Kuzuhara A. Analysis of internal structure changes in black human hair keratin fibers resulting from bleaching treatments using Raman spectroscopy. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2013.04.079] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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15
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Schütz R, Bertinetti L, Rabin I, Fratzl P, Masic A. Quantifying degradation of collagen in ancient manuscripts: the case of the Dead Sea Temple Scroll. Analyst 2013; 138:5594-9. [DOI: 10.1039/c3an00609c] [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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Comparative study on keratin structural changes in onychomycosis and normal human finger nail specimens by Raman spectroscopy. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2013.01.051] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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17
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Analysis of heterogeneous reaction between reducing agents and keratin fibers using Raman spectroscopy and microspectrophotometry. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2012.12.040] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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18
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Ye S, Wei F, Li H, Tian K, Luo Y. Structure and Orientation of Interfacial Proteins Determined by Sum Frequency Generation Vibrational Spectroscopy. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2013; 93:213-55. [DOI: 10.1016/b978-0-12-416596-0.00007-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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19
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Zhang C, Myers J, Chen Z. Elucidation of molecular structures at buried polymer interfaces and biological interfaces using sum frequency generation vibrational spectroscopy. SOFT MATTER 2013; 9:4738-4761. [PMID: 23710244 PMCID: PMC3661304 DOI: 10.1039/c3sm27710k] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Sum frequency generation (SFG) vibrational spectroscopy has been developed into an important technique to study surfaces and interfaces. It can probe buried interfaces in situ and provide molecular level structural information such as the presence of various chemical moieties, quantitative molecular functional group orientation, and time dependent kinetics or dynamics at such interfaces. This paper focuses on these three most important advantages of SFG and reviews some of the recent progress in SFG studies on interfaces related to polymer materials and biomolecules. The results discussed here demonstrate that SFG can provide important molecular structural information of buried interfaces in situ and in real time, which is difficult to obtain by other surface sensitive analytical techniques.
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Affiliation(s)
- Chi Zhang
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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20
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Bito K, Okuno M, Kano H, Tokuhara S, Naito S, Masukawa Y, Leproux P, Couderc V, Hamaguchi HO. Protein Secondary Structure Imaging with Ultrabroadband Multiplex Coherent Anti-Stokes Raman Scattering (CARS) Microspectroscopy. J Phys Chem B 2012; 116:1452-7. [DOI: 10.1021/jp210914x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Kotatsu Bito
- Analytical Science
Research
Laboratories, Kao Corporation, Akabane
2606, Ichikai, Haga, Tochigi 321-3497, Japan
- Department of Chemistry, School
of Science, The University of Tokyo, Hongo
7-3-1, Bunkyo, Tokyo 113-0033, Japan
| | - Masanari Okuno
- Department of Chemistry, School
of Science, The University of Tokyo, Hongo
7-3-1, Bunkyo, Tokyo 113-0033, Japan
| | - Hideaki Kano
- Department of Chemistry, School
of Science, The University of Tokyo, Hongo
7-3-1, Bunkyo, Tokyo 113-0033, Japan
| | - Shihomi Tokuhara
- Analytical Science
Research
Laboratories, Kao Corporation, Akabane
2606, Ichikai, Haga, Tochigi 321-3497, Japan
| | - Satoru Naito
- Analytical Science
Research
Laboratories, Kao Corporation, Akabane
2606, Ichikai, Haga, Tochigi 321-3497, Japan
| | - Yoshinori Masukawa
- Analytical Science
Research
Laboratories, Kao Corporation, Akabane
2606, Ichikai, Haga, Tochigi 321-3497, Japan
| | - Philippe Leproux
- Institut de Recherche XLIM, UMR CNRS 6172, 123 Avenue Albert Thomas, 87060
Limoges Cedex, France
- LEUKOS, ESTER Technopole, 1 Avenue d’Ester,
87069 Limoges Cedex, France
| | - Vincent Couderc
- Institut de Recherche XLIM, UMR CNRS 6172, 123 Avenue Albert Thomas, 87060
Limoges Cedex, France
| | - Hiro-o Hamaguchi
- Department of Chemistry, School
of Science, The University of Tokyo, Hongo
7-3-1, Bunkyo, Tokyo 113-0033, Japan
- Institute of Molecular Science
and Department of Applied Chemistry, National Chiao Tung University, Ta Hsueh Road 1001, Hsinchu 300, Taiwan
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21
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Masic A, Bertinetti L, Schuetz R, Galvis L, Timofeeva N, Dunlop JWC, Seto J, Hartmann MA, Fratzl P. Observations of multiscale, stress-induced changes of collagen orientation in tendon by polarized Raman spectroscopy. Biomacromolecules 2011; 12:3989-96. [PMID: 21954830 DOI: 10.1021/bm201008b] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Collagen is a versatile structural molecule in nature and is used as a building block in many highly organized tissues, such as bone, skin, and cornea. The functionality and performance of these tissues are controlled by their hierarchical organization ranging from the molecular up to macroscopic length scales. In the present study, polarized Raman microspectroscopic and imaging analyses were used to elucidate collagen fibril orientation at various levels of structure in native rat tail tendon under mechanical load. In situ humidity-controlled uniaxial tensile tests have been performed concurrently with Raman confocal microscopy to evaluate strain-induced chemical and structural changes of collagen in tendon. The methodology is based on the sensitivity of specific Raman scattering bands (associated with distinct molecular vibrations, such as the amide I) to the orientation and the polarization direction of the incident laser light. Our results, based on the changing intensity of Raman lines as a function of orientation and polarization, support a model where the crimp and gap regions of collagen hierarchical structure are straightened at the tissue and molecular level, respectively. However, the lack of measurable changes in Raman peak positions throughout the whole range of strains investigated indicates that no significant changes of the collagen backbone occurs with tensing and suggests that deformation is rather redistributed through other levels of the hierarchical structure.
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Affiliation(s)
- Admir Masic
- Department of Biomaterials, Max-Planck-Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany
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22
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Ye S, Nguyen KT, Le Clair SV, Chen Z. In situ molecular level studies on membrane related peptides and proteins in real time using sum frequency generation vibrational spectroscopy. J Struct Biol 2009; 168:61-77. [PMID: 19306928 PMCID: PMC2753614 DOI: 10.1016/j.jsb.2009.03.006] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 03/11/2009] [Accepted: 03/13/2009] [Indexed: 12/11/2022]
Abstract
Sum frequency generation (SFG) vibrational spectroscopy has been demonstrated to be a powerful technique to study the molecular structures of surfaces and interfaces in different chemical environments. This review summarizes recent SFG studies on hybrid bilayer membranes and substrate-supported lipid monolayers and bilayers, the interaction between peptides/proteins and lipid monolayers/bilayers, and bilayer perturbation induced by peptides/proteins. To demonstrate the ability of SFG to determine the orientations of various secondary structures, studies on the interactions between different peptides/proteins (melittin, G proteins, alamethicin, and tachyplesin I) and lipid bilayers are discussed. Molecular level details revealed by SFG in these studies show that SFG can provide a unique understanding on the interactions between a lipid monolayer/bilayer and peptides/proteins in real time, in situ and without any exogenous labeling.
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Affiliation(s)
- Shuji Ye
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109
| | - Khoi Tan Nguyen
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109
| | | | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109
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23
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Nguyen KT, Le Clair SV, Ye S, Chen Z. Orientation determination of protein helical secondary structures using linear and nonlinear vibrational spectroscopy. J Phys Chem B 2009; 113:12169-80. [PMID: 19650636 PMCID: PMC2799944 DOI: 10.1021/jp904153z] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this paper, we systematically presented the orientation determination of protein helical secondary structures using vibrational spectroscopic methods, particularly, nonlinear sum frequency generation (SFG) vibrational spectroscopy, along with linear vibrational spectroscopic techniques such as infrared spectroscopy and Raman scattering. SFG amide I signals can be collected using different polarization combinations of the input laser beams and output signal beam to measure the second-order nonlinear optical susceptibility components of the helical amide I modes, which are related to their molecular hyperpolarizability elements through the orientation distribution of these helices. The molecular hyperpolarizability elements of amide I modes of a helix can be calculated based on the infrared transition dipole moment and Raman polarizability tensor of the helix; these quantities are determined by using the bond additivity model to sum over the individual infrared transition dipole moments and Raman polarizability tensors, respectively, of the peptide units (or the amino acid residues). The computed overall infrared transition dipole moment and Raman polarizability tensor of a helix can be validated by experimental data using polarized infrared and polarized Raman spectroscopy on samples with well-aligned helical structures. From the deduced SFG hyperpolarizability elements and measured SFG second-order nonlinear susceptibility components, orientation information regarding helical structures can be determined. Even though such orientation information can also be measured using polarized infrared or polarized Raman amide I signals, SFG has a much lower detection limit, which can be used to study the orientation of a helix when its surface coverage is much lower than a monolayer. In addition, the combination of different vibrational spectroscopic techniques, for example, SFG and attenuated total reflectance Fourier transform infrared spectroscopy, provides more measured parameters for orientation determination, aiding in the deduction of more complicated orientation distributions. In this paper, we discussed two types of helices, the alpha-helix and 3-10 helix. However, the orientation determination method presented here is general and thus can be applied to study other helices as well. The calculations of SFG amide I hyperpolarizability components for alpha-helical and 3-10 helical structures with different chain lengths have also been performed. It was found that when the helices reached a certain length, the number of peptide units in the helix should not alter the data analysis substantially. It was shown in the calculation, however, that when the helix chain is short, the SFG hyperpolarizability component ratios can vary substantially when the chain length is changed. Because 3-10 helical structures can be quite short in proteins, the orientation determination for a short 3-10 helix needs to take into account the number of peptide units in the helix.
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Affiliation(s)
- Khoi Tan Nguyen
- Department of Chemistry, 930 North University Avenue, University of Michigan, Ann Arbor, MI 48109
| | - Stéphanie V. Le Clair
- Department of Chemistry, 930 North University Avenue, University of Michigan, Ann Arbor, MI 48109
| | - Shuji Ye
- Department of Chemistry, 930 North University Avenue, University of Michigan, Ann Arbor, MI 48109
| | - Zhan Chen
- Department of Chemistry, 930 North University Avenue, University of Michigan, Ann Arbor, MI 48109
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24
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Rizzo N, Gardner K, Walls D, Keiper-Hrynko N, Ganzke T, Hallahan D. Characterization of the structure and composition of gecko adhesive setae. J R Soc Interface 2009; 3:441-51. [PMID: 16849272 PMCID: PMC1578751 DOI: 10.1098/rsif.2005.0097] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The ability of certain reptiles to adhere to vertical (and hang from horizontal) surfaces has been attributed to the presence of specialized adhesive setae on their feet. Structural and compositional studies of such adhesive setae will contribute significantly towards the design of biomimetic fibrillar adhesive materials. The results of electron microscopy analyses of the structure of such setae are presented, indicating their formation from aggregates of proteinaceous fibrils held together by a matrix and potentially surrounded by a limiting proteinaceous sheath. Microbeam X-ray diffraction analysis has shown conclusively that the only ordered protein constituent in these structures exhibits a diffraction pattern characteristic of beta-keratin. Raman microscopy of individual setae, however, clearly shows the presence of additional protein constituents, some of which may be identified as alpha-keratins. Electrophoretic analysis of solubilized setal proteins supports these conclusions, indicating the presence of a group of low-molecular-weight beta-keratins (14-20 kDa), together with alpha-keratins, and this interpretation is supported by immunological analyses.
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Ackermann K, Koster J, Schlücker S. Conformations and vibrational properties of disulfide bridges: Potential energy distribution in the model system diethyl disulfide. Chem Phys 2009. [DOI: 10.1016/j.chemphys.2008.11.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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26
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Green E, Ellis R, Winlove P. The molecular structure and physical properties of elastin fibers as revealed by Raman microspectroscopy. Biopolymers 2008; 89:931-40. [DOI: 10.1002/bip.21037] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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27
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Ly E, Piot O, Durlach A, Bernard P, Manfait M. Polarized Raman microspectroscopy can reveal structural changes of peritumoral dermis in basal cell carcinoma. APPLIED SPECTROSCOPY 2008; 62:1088-1094. [PMID: 18926017 DOI: 10.1366/000370208786049187] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Polarized Raman microspectroscopy can provide precious information regarding the orientation and ordering of the molecules in a sample without staining or particular preparation. This technique is used for the first time on a human skin section to probe the molecular modifications of the surrounding dermis in superficial basal cell carcinoma. Spectra using polarized and conventional Raman microspectroscopies were recorded on dermis bordering either the tumor or healthy epidermis. Band areas and spectral decomposition on selected vibrations were computed. Significant differences in dermal collagen vibration bands are detected using both polarized and conventional micro-spectroscopies, but the spectral changes between tumor and healthy tissues are enhanced using polarized Raman microspectroscopy. The analysis of these spectral differences highlights structural modifications of the triple helix of collagen. We see polarized Raman microspectroscopy as a potential tool that could be implemented for clinical analyses to guide clinicians and surgeons in the treatment of aggressive skin cancers. The information obtainable could also help better elucidate the molecular mechanisms induced in basal cell carcinoma development.
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Affiliation(s)
- Elodie Ly
- Unité MéDIAN UMR CNRS 6237 MEDyC, UFR de Pharmacie, IFR 53, Université Reims-Champagne Ardenne, 51 rue Cognacq-Jay, 51096 Reims Cedex, France
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Ackermann KR, Koster J, Schlücker S. Polarized Raman microspectroscopy on intact human hair. JOURNAL OF BIOPHOTONICS 2008; 1:419-424. [PMID: 19343665 DOI: 10.1002/jbio.200810015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Polarization-resolved Raman microspectroscopy with near-infrared laser excitation was applied to intact human hair in order to non-invasively investigate the conformation and orientation of the polypeptide chains. By varying the orientation of the hair shaft relative to the polarization directions of the laser/analyzer, a set of four polarized Raman spectra is obtained; this allows to simultaneously determine both the secondary structure of hair proteins and the orientation of the polypeptide strands relative to the axis of the hair shaft. For the amide I band, results from a quantitative analysis of the polarized Raman spectra are compared with theoretically expected values for fibers with uniaxial symmetry. Based on the polarization behavior of the amide I band and further vibrational bands, a partial ordering of alpha-helical polypeptide strands parallel to the hair shaft can be concluded. We suggest that this microspectroscopic approach may be used for human hair diagnostics by detecting structural or orientational alterations of keratins.
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Affiliation(s)
- Katrin R Ackermann
- Institut für Physikalische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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Wang J, Lee SH, Chen Z. Quantifying the Ordering of Adsorbed Proteins In Situ. J Phys Chem B 2008; 112:2281-90. [DOI: 10.1021/jp077556u] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jie Wang
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Sang-Ho Lee
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
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30
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Sorption of Cu2+ and Zn2+ by Natural Biomaterial: Duck Feather. Appl Biochem Biotechnol 2007; 142:168-78. [DOI: 10.1007/s12010-007-0015-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2006] [Revised: 07/26/2006] [Accepted: 08/02/2006] [Indexed: 10/23/2022]
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31
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Chen X, Wang J, Boughton AP, Kristalyn CB, Chen Z. Multiple orientation of melittin inside a single lipid bilayer determined by combined vibrational spectroscopic studies. J Am Chem Soc 2007; 129:1420-7. [PMID: 17263427 DOI: 10.1021/ja067446l] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Despite the availability of several mature structure determination techniques for bulk proteins, determination of structural and orientational information of interfacial proteins, e.g., in cell membranes or on biomaterial surfaces, remains a difficult problem. We combine sum frequency generation (SFG) vibrational spectroscopy with attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) to investigate the orientation of alpha-helical peptides reconstituted in substrate supported lipid bilayers. Melittin was chosen as a model for alpha-helical peptides, and its orientation when interacting with a supported 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG) bilayer has been examined. Through polarization analysis using amide I signals obtained from both SFG and ATR-FTIR measurements, the orientation distribution of melittin inside a DPPG bilayer was deduced using several trial distribution functions. Melittin was modeled as either an ideal helix or a helix with a bent structure. It was found that a simple distribution function such as a delta-distribution or a Gaussian distribution was not adequate to describe the melittin orientation distribution inside a DPPG bilayer. Instead, two populations of melittin, corresponding to two melittin-bilayer association states, could be used to interpret the experimentally observed result. The method employed in this study demonstrates the feasibility of acquiring a more accurate orientation distribution of peptides/proteins in situ using a combination of vibrational spectroscopic techniques without exogenous labeling.
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Affiliation(s)
- Xiaoyun Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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Rousseau ME, Beaulieu L, Lefèvre T, Paradis J, Asakura T, Pézolet M. Characterization by Raman Microspectroscopy of the Strain-Induced Conformational Transition in Fibroin Fibers from the Silkworm Samia cynthia ricini. Biomacromolecules 2006; 7:2512-21. [PMID: 16961312 DOI: 10.1021/bm060280w] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Raman microspectroscopy has been used to quantitatively study the effect of a mechanical deformation on the conformation and orientation of Samia cynthia ricini (S. c. ricini) silk fibroin. Samples were obtained from the aqueous solution stored in the silk gland and stretched at draw ratios (lambda) ranging from 0 to 11. Using an appropriate band decomposition procedure, polarized and orientation-insensitive spectra have been analyzed to determine order parameters and the content of secondary structures, respectively. The data unambiguously show that, in response to mechanical deformation, S. c. ricini fibroin undergoes a cooperative alpha-helix to beta-sheet conformational transition above a critical draw ratio of 4. The alpha-helix content decreases from 33 to 13% when lambda increases from 0 to 11, while the amount of beta-sheets increases from 15 to 37%. In comparison, cocoon silk is devoid of alpha-helical structure and always contains a larger amount of beta-sheets. Although the presence of isosbestic points in different spectral regions reveals that the conformational change induced by mechanical deformation is a two-state process, our results suggest that part of the glycine residues might be incorporated into beta-poly(alanine) structures. The beta-sheets are initially isotropically distributed and orient along the fiber axis as lambda increases, but do not reach the high level of orientation found in the cocoon fiber. The increase in the orientation level of the beta-sheets is found to be concomitant with the alpha --> beta conformational conversion, whereas alpha-helices do not orient under the applied strain but are rather readily converted into beta-sheets. The components assigned to turns exhibit a small orientation perpendicular to the fiber axis in stretched samples, showing that, overall, the polypeptide chains are aligned along the stretching direction. Our results suggest that, in nature, factors other than stretching contribute to the optimization of the amount of beta-sheets and the high degree of orientation found in natural cocoon silk.
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Affiliation(s)
- Marie-Eve Rousseau
- Département de Chimie et CERSIM, Université Laval, Québec, QC, Canada G1K 7P4
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Kuzuhara A. Analysis of structural changes in bleached keratin fibers (black and white human hair) using Raman spectroscopy. Biopolymers 2006; 81:506-14. [PMID: 16425172 DOI: 10.1002/bip.20453] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
To investigate the influence of bleaching treatments on keratin fibers, the structure of cross-sections at various depths of bleached human hair (black and white human hair) was directly analyzed without isolating the cuticle and cortex, using Raman spectroscopy. The S-S band intensity existing from the cuticle region to the center of cortex region of virgin white human hair decreased, while the S-O band intensity at 1040 cm(-1), assigned to cysteic acid, increased by performing the bleaching treatment. Especially, the S-O band intensity of the cuticle region increased remarkably compared with that of the cortex region. Also, the amide III (unordered) band intensity in the cortex region increased, indicating that some of the proteins existing throughout the cortex region changed to the random coil form. Moreover, it has been found that the S-S band intensity existing from the cuticle region to the center of the cortex region of the virgin black human hair decreased remarkably, while the S-O band intensity increased significantly compared with that of the virgin white human hair by performing the bleaching treatment. From these experiments, we concluded that the melanin granules including metal ions act as a decomposition accelerator for the oxidizing agent, thereby leading to a higher level of disulfide (-SS-) group cleavage in the black human hair compared with that of the white human hair.
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Affiliation(s)
- Akio Kuzuhara
- Central Research Laboratories, Mandom Corp., 5-12, Juniken-cho, Chuo-ku, Osaka 540-8530, Japan.
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Schlücker S, Liang C, Strehle KR, DiGiovanna JJ, Kraemer KH, Levin IW. Conformational differences in protein disulfide linkages between normal hair and hair from subjects with trichothiodystrophy: A quantitative analysis by Raman microspectroscopy. Biopolymers 2006; 82:615-22. [PMID: 16557500 DOI: 10.1002/bip.20515] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Raman spectra of normal hair shafts and hair shafts from patients exhibiting trichothiodystrophy (TTD) were obtained using line focus laser illumination. Because hair from TTD patients has a significant decrease in the content of the sulfur-containing amino acids in comparison to normal hair, the 550-500 cm(-1) disulfide stretching mode region of the Raman spectrum was examined in detail. A quantitative spectral analysis demonstrates significant increases in the two energetically less favored gauche-gauche-trans (g-g-t) and trans-gauche-trans (t-g-t) forms. These observations suggest that the increased amounts of these less stable disulfide conformers are contributing factors to or associated with the hair brittleness observed for this congenital disorder. Structure-spectra correlations for the three dominant disulfide conformers are confirmed by quantum chemical calculations using modern density functional theory (DFT).
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Affiliation(s)
- S Schlücker
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Jastrzebska M, Zalewska-Rejdak J, Wrzalik R, Kocot A, Barwiński B, Mróz I, Cwalina B. Dimethyl suberimidate cross-linked pericardium tissue: Raman spectroscopic and atomic force microscopy investigations. J Mol Struct 2005. [DOI: 10.1016/j.molstruc.2004.11.040] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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36
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Kuzuhara A, Hori T. Reduction mechanism ofL-cysteine on keratin fibers using microspectrophotometry and Raman spectroscopy. Biopolymers 2005; 79:324-34. [PMID: 16130128 DOI: 10.1002/bip.20362] [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: 11/08/2022]
Abstract
In order to investigate the reduction mechanism of L-cysteine (Cys) on keratin fibers, cross-sectional samples of virgin white human hair treated with Cys were prepared. The heterogeneous reaction between Cys and keratin fibers involving the diffusion of Cys into human hair was analyzed at the molecular level using microspectrophotometry and Raman spectroscopy. The diffusion pattern of Cys into human hair showed non-Fickian type characteristics, thus indicating the free amino groups of electrostatically interacted with the anionic ions of the fiber surface. The disconnected relative concentration of -SS- groups at various depths of the hair samples with pH 9.0 was less than the Cys relative concentration, indicating that the reaction rate (the disconnection of -SS- groups) was slower than the diffusion rate of Cys into human hair. From these experiments, we concluded that the free amino groups of Cys electrostatically interacted with the anionic ions of the fiber surface, thereby decreasing the reaction rate (the disconnection of -SS- groups) of Cys at pH 9.0.
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Affiliation(s)
- Akio Kuzuhara
- Central Research Laboratories, Mandom Corp., 5-12, Osaka 540-8530, Japan.
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Kuzuhara A. Analysis of structural change in keratin fibers resulting from chemical treatments using Raman spectroscopy. Biopolymers 2005; 77:335-44. [PMID: 15739182 DOI: 10.1002/bip.20221] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In order to investigate the influence of chemical treatments (reduction, heating, and oxidation) on keratin fibers, the structure of virgin white human hair resulting from a permanent hair straightening process at various depths of cross-sectional samples was directly analyzed without isolating the cuticle and cortex, using Raman spectroscopy. The band shape of the cuticle was different from that of the cortex, and the cuticle had a more amorphous structure, compared with the cortex. The S-S band intensity existing in the hair surface remarkably decreased, while the S-S band intensity in the hair center was not changed by performing the reduction process. In the case of heating the keratin fibers after the reduction process, this tendency was unchanged. On the other hand, the amide III (unordered) band intensity in the cortex region increased, indicating that proteins existing throughout the cortex region caused a change to the random coil form. Moreover, approximately 95% of the disconnected -SS- groups were clearly reconnected by performing the oxidation process after heating (the degree of reconnection of -SS- groups was about 90%, in the case of oxidizing after reduction). From these experiments, we concluded that the heat treatment process in the permanent hair straightening treatment caused the randomization of proteins existing throughout the cortex region, thereby contributing to the acceleration of the reconnection of -SS- groups during the oxidation process.
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Affiliation(s)
- Akio Kuzuhara
- Central Research Laboratories, Mandom Corp., 5-12, Juniken-cho, Chuo-ku, Osaka 540-8530, Japan.
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38
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Kuzuhara A. Protein structural changes in keratin fibers induced by chemical modification using 2-iminothiolane hydrochloride: A Raman spectroscopic investigation. Biopolymers 2005; 79:173-84. [PMID: 16145652 DOI: 10.1002/bip.20329] [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: 11/08/2022]
Abstract
For the purpose of investigating in detail the influence of chemical modification using 2-iminothiolane hydrochloride (2-IT) on keratin fibers, the structure of cross-sections at various depths of white human hair, treated with 2-IT and then oxidized, was directly analyzed without isolating the cuticle and cortex, using Raman spectroscopy. In particular, the beta-sheet and/or random coil content (beta/R) and the alpha-helix (alpha) content in human hair fibers were estimated by amide I band analysis. The S-S band intensity, amide III (unordered) band intensity, and beta/R content existing from the cuticle region to the center of cortex region of virgin white human hair remarkably increased by performing the chemical modification using 2-IT. On the other hand, not only the S-S band intensity, but also S-O band intensity existing throughout the cortex region of the bleached (damaged) white human hair increased by performing chemical modification using 2-IT. In particular, beta/R content existing throughout the cortex region of the bleached white human hair decreased, while the skeletal C-C stretch (alpha) band intensity at 935 cm(-1) and the alpha content remarkably increased. This indicates a secondary structural change from the random coil form to the alpha-helix form in the proteins existing throughout the cortex region. From these experiments, we concluded that the formation of new disulfide (-SS-) groups resulting from chemical modification using 2-IT induced the secondary structural changes of proteins existing throughout the cortex region.
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Affiliation(s)
- Akio Kuzuhara
- Central Research Laboratories, Mandom Corp., 5-12, Juniken-cho, Chuo-ku, Osaka 540-8530, Japan.
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