title: Molecular tandem repeat strategy for elucidating mechanical properties of high-strength proteins.
abstract: Many globular and structural proteins have repetitions in their sequences or structures. However, a clear relationship between these repeats and their contribution to the mechanical properties remains elusive. We propose a new approach for the design and production of synthetic polypeptides that comprise one or more tandem copies of a single unit with distinct amorphous and ordered regions. Our designed sequences are based on a structural protein produced in squid suction cups that has a segmented copolymer structure with amorphous and crystalline domains. We produced segmented polypeptides with varying repeat number, while keeping the lengths and compositions of the amorphous and crystalline regions fixed. We showed that mechanical properties of these synthetic proteins could be tuned by modulating their molecular weights. Specifically, the toughness and extensibility of synthetic polypeptides increase as a function of the number of tandem repeats. This result suggests that the repetitions in native squid proteins could have a genetic advantage for increased toughness and flexibility.
authors.affiliation: Materials Research Institute, Pennsylvania State University, University Park, PA 16802; Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802;
authors.forename: Huihun
authors.initials: H
authors.lastname: Jung
authors.affiliation: Materials Research Institute, Pennsylvania State University, University Park, PA 16802; Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802;
authors.forename: Abdon
authors.initials: A
authors.lastname: Pena-Francesch
authors.affiliation: Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802; The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802;
authors.forename: Alham
authors.initials: A
authors.lastname: Saadat
authors.affiliation: Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802; The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802; Bioinformatics Consulting Center, Pennsylvania State University, University Park, PA 16802;
authors.forename: Aswathy
authors.initials: A
authors.lastname: Sebastian
authors.affiliation: Department of Biology, Pennsylvania State University, University Park, PA 16802.
authors.forename: Dong Hwan
authors.initials: DH
authors.lastname: Kim
authors.affiliation: Materials Research Institute, Pennsylvania State University, University Park, PA 16802; Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802;
authors.forename: Reginald F
authors.initials: RF
authors.lastname: Hamilton
authors.affiliation: Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802; The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802; Bioinformatics Consulting Center, Pennsylvania State University, University Park, PA 16802;
authors.forename: Istvan
authors.initials: I
authors.lastname: Albert
authors.affiliation: Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802; The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802; bda3@psu.edu mdemirel@engr.psu.edu.
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Allen
authors.affiliation: Materials Research Institute, Pennsylvania State University, University Park, PA 16802; Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802; The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802; bda3@psu.edu mdemirel@engr.psu.edu.
authors.forename: Melik C
authors.initials: MC
authors.lastname: Demirel
mesh_terms: D000818:Animals; D049832:Decapodiformes / Q000235:genetics*; D055595:Mechanical Phenomena; D010455:Peptides / Q000737:chemistry / Q000235:genetics; D011506:Proteins / Q000737:chemistry / Q000235:genetics; D020080:Tandem Repeat Sequences
chemical_list: D010455:Peptides; D011506:Proteins
keywords: high strength; protein; squid ring teeth; tandem repeat; thermoplastic