title: Antifreeze activity enhancement by site directed mutagenesis on an antifreeze protein from the beetle Rhagium mordax.
abstract: The ice binding motifs of insect antifreeze proteins (AFPs) mainly consist of repetitive TxT motifs aligned on a flat face of the protein. However, these motifs often contain non-threonines that disrupt the TxT pattern. We substituted two such disruptive amino acids located in the ice binding face of an AFP from Rhagium mordax with threonine. Furthermore, a mutant with an extra ice facing TxT motif was constructed. These mutants showed enhanced antifreeze activity compared to the wild type at low concentrations. However, extrapolating the data indicates that the wild type will become the most active at concentrations above 270 μmol.
authors.affiliation: Department of Science, Systems and Models, Roskilde University, Universitetsvej 1, P.O. Box 260, Building 18.1, DK-4000 Roskilde, Denmark. Electronic address: dsf@ruc.dk.
authors.forename: Dennis Steven
authors.initials: DS
authors.lastname: Friis
authors.affiliation: Department of Science, Systems and Models, Roskilde University, Universitetsvej 1, P.O. Box 260, Building 18.1, DK-4000 Roskilde, Denmark.
authors.forename: Erlend
authors.initials: E
authors.lastname: Kristiansen
authors.affiliation: Department of Chemical and Biochemical Engineering, Center for Energy Resource Engineering, Technical University of Denmark, Søltoftsplads, Building 229, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Nicolas
authors.initials: N
authors.lastname: von Solms
authors.affiliation: Department of Science, Systems and Models, Roskilde University, Universitetsvej 1, P.O. Box 260, Building 18.1, DK-4000 Roskilde, Denmark.
authors.forename: Hans
authors.initials: H
authors.lastname: Ramløv
mesh_terms: D000818:Animals; D021301:Antifreeze Proteins / Q000737:chemistry* / Q000235:genetics; D001665:Binding Sites; D001517:Coleoptera; D005615:Freezing; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D017433:Protein Structure, Secondary
chemical_list: D021301:Antifreeze Proteins; D019476:Insect Proteins
keywords: Antifreeze protein; Site directed mutagenesis; Thermal hysteresis