title: Unexpected behavior of irradiated spider silk links conformational freedom to mechanical performance.
abstract: Silk fibers from Argiope trifasciata and Nephila inaurata orb-web weaving spiders were UV irradiated to modify the molecular weight of the constituent proteins. Fibers were characterized either as forcibly silked or after being subjected to maximum supercontraction. The effect of irradiation on supercontraction was also studied, both in terms of the percentage of supercontraction and the tensile properties exhibited by irradiated and subsequently supercontracted fibers. The effects of UV exposure at the molecular level were assessed by polyacrylamide gel electrophoresis and mass spectrometry. It is shown that UV-irradiated fibers show a steady decrease in their main tensile parameters, most notably, tensile strength and strain. The combination of the mechanical and biochemical data suggests that the restricted conformational freedom of the proteins after UV irradiation is critical in the reduction of these properties. Consequently, an adequate topological organization of the protein chains emerges as a critical design principle in the performance of spider silk.
authors.affiliation: Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid, Spain. jperez@mater.upm.es.
authors.forename: G Belén
authors.initials: GB
authors.lastname: Perea
authors.forename: Concepción
authors.initials: C
authors.lastname: Solanas
authors.forename: Gustavo R
authors.initials: GR
authors.lastname: Plaza
authors.forename: Gustavo V
authors.initials: GV
authors.lastname: Guinea
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Jorge
authors.forename: Jesús
authors.initials: J
authors.lastname: Vázquez
authors.forename: Jorge M
authors.initials: JM
authors.lastname: Pérez Mateos
authors.forename: Núria
authors.initials: N
authors.lastname: Marí-Buyé
authors.forename: Manuel
authors.initials: M
authors.lastname: Elices
authors.forename: José
authors.initials: J
authors.lastname: Pérez-Rigueiro
mesh_terms: D000818:Animals; D019476:Insect Proteins / Q000737:chemistry* / Q000528:radiation effects; D011487:Protein Conformation; D047011:Silk / Q000737:chemistry* / Q000528:radiation effects; D013112:Spiders; D013718:Tensile Strength; D014466:Ultraviolet Rays
chemical_list: D019476:Insect Proteins; D047011:Silk