title: Ordering of protein and water molecules at their interfaces with chitin nano-crystals.
abstract: Synchrotron X-ray diffraction was applied to study the structure of biogenic α-chitin crystals composing the tendon of the spider Cupiennius salei. Measurements were carried out on pristine chitin crystals stabilized by proteins and water, as well as after their deproteinization and dehydration. We found substantial shifts (up to Δq/q=9% in the wave vector in q-space) in the (020) diffraction peak position between intact and purified chitin samples. However, chitin lattice parameters extracted from the set of reflections (hkl), which did not contain the (020)-reflection, showed no systematic variation between the pristine and the processed samples. The observed shifts in the (020) peak position are discussed in terms of the ordering-induced modulation of the protein and water electron density near the surface of the ultra-thin chitin fibrils due to strong protein/chitin and water/chitin interactions. The extracted modulation periods can be used as a quantitative parameter characterizing the interaction length.
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany.
authors.forename: Clara
authors.initials: C
authors.lastname: Valverde Serrano
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany.
authors.forename: Hanna
authors.initials: H
authors.lastname: Leemreize
authors.affiliation: Department of Mechanical Engineering, Ben-Gurion University, Beer Sheba 84105, Israel; Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany.
authors.forename: Benny
authors.initials: B
authors.lastname: Bar-On
authors.affiliation: Department of Neurobiology, Faculty of Life Sciences, University of Vienna, 1090 Vienna, Austria.
authors.forename: Friedrich G
authors.initials: FG
authors.lastname: Barth
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Fratzl
authors.affiliation: Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel.
authors.forename: Emil
authors.initials: E
authors.lastname: Zolotoyabko
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany. Electronic address: yael.politi@mpikg.mpg.de.
authors.forename: Yael
authors.initials: Y
authors.lastname: Politi
mesh_terms: D000818:Animals; D002686:Chitin / Q000737:chemistry*; D019476:Insect Proteins / Q000737:chemistry*; D008956:Models, Chemical; D053758:Nanoparticles / Q000737:chemistry*; D012542:Scattering, Radiation; D013059:Spectrum Analysis, Raman; D013112:Spiders; D013710:Tendons / Q000737:chemistry; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D019476:Insect Proteins; D014867:Water; D002686:Chitin
keywords: Chitin; Chitin/protein interaction; Chitin/water interaction; X-ray diffraction