title: Identification and dynamics of polyglycine II nanocrystals in Argiope trifasciata flagelliform silk.
abstract: Spider silks combine a significant number of desirable characteristics in one material, including large tensile strength and strain at breaking, biocompatibility, and the possibility of tailoring their properties. Major ampullate gland silk (MAS) is the most studied silk and their properties are explained by a double lattice of hydrogen bonds and elastomeric protein chains linked to polyalanine β-nanocrystals. However, many basic details regarding the relationship between composition, microstructure and properties in silks are still lacking. Here we show that this relationship can be traced in flagelliform silk (Flag) spun by Argiope trifasciata spiders after identifying a phase consisting of polyglycine II nanocrystals. The presence of this phase is consistent with the dominant presence of the -GGX- and -GPG- motifs in its sequence. In contrast to the passive role assigned to polyalanine nanocrystals in MAS, polyglycine II nanocrystals can undergo growing/collapse processes that contribute to increase toughness and justify the ability of Flag to supercontract.
authors.affiliation: 1] Centro de Tecnología Biomédica. Universidad Politécnica de Madrid. 28223 Pozuelo de Alarcón (Madrid). Spain [2] Departamento de Ciencia de Materiales. ETSI Caminos, Canales y Puertos. Universidad Politécnica de Madrid. 28040. Madrid. Spain.
authors.forename: G B
authors.initials: GB
authors.lastname: Perea
authors.forename: C
authors.initials: C
authors.lastname: Riekel
authors.forename: G V
authors.initials: GV
authors.lastname: Guinea
authors.forename: R
authors.initials: R
authors.lastname: Madurga
authors.forename: R
authors.initials: R
authors.lastname: Daza
authors.forename: M
authors.initials: M
authors.lastname: Burghammer
authors.forename: C
authors.initials: C
authors.lastname: Hayashi
authors.forename: M
authors.initials: M
authors.lastname: Elices
authors.forename: G R
authors.initials: GR
authors.lastname: Plaza
authors.forename: J
authors.initials: J
authors.lastname: Pérez-Rigueiro
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D006860:Hydrogen Bonding; D018625:Microscopy, Atomic Force; D053758:Nanoparticles / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D047011:Silk / Q000737:chemistry* / Q000378:metabolism; D013112:Spiders / Q000378:metabolism*
chemical_list: C404864:FLAG protein, Nephila; D010455:Peptides; D011506:Proteins; D047011:Silk; C011080:polyglycine