title: Annealing condition influences thermal hysteresis of fungal type ice-binding proteins.
abstract: The Antarctic sea ice diatom Navicular glaciei produced ice-binding protein (NagIBP) that is similar to the antifreeze protein (TisAFP) from snow mold Typhula ishikariensis. In the thermal hysteresis range of NagIBP, ice growth was completely inhibited. At the freezing point, the ice grew in a burst to 6 direction perdicular to the c-axis of ice crystal. This burst pattern is similar to TisAFP and other hyperactive AFPs. The thermal hysteresis of NagIBP and TisAFP could be increased by decreasing a cooling rate to allow more time for the proteins to bind ice. This suggests the possible second binding of proteins occurs on the ice surface, which might increase the hysteresises to a sufficient level to prevent freezing of the brine pockets which habitat of N. glaciei. The secondary ice binding was described as that after AFP molecules bind onto the flat ice plane irreversibly, which was based on adsorption-inhibition mechanism model at the ice-water interface, convex ice front was formed and overgrew during normal TH measurement (no annealing) until uncontrolled growth at the nonequilibrium freezing point. The results suggested that NagIBP is a hyperactive AFP that is expressed for freezing avoidance.
authors.affiliation: Graduate School of Life Science, Hokkaido University, N10W8, Kita-ku, Sapporo 060-0810, Japan.
authors.forename: Nan
authors.initials: N
authors.lastname: Xiao
authors.affiliation: Graduate School of Life Science, Hokkaido University, N10W8, Kita-ku, Sapporo 060-0810, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Hanada
authors.affiliation: Graduate School of Life Science, Hokkaido University, N10W8, Kita-ku, Sapporo 060-0810, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Seki
authors.affiliation: Graduate School of Life Science, Hokkaido University, N10W8, Kita-ku, Sapporo 060-0810, Japan; Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo 062-8517, Japan.
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Kondo
authors.affiliation: Graduate School of Life Science, Hokkaido University, N10W8, Kita-ku, Sapporo 060-0810, Japan; Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo 062-8517, Japan.
authors.forename: Sakae
authors.initials: S
authors.lastname: Tsuda
authors.affiliation: Graduate School of Life Science, Hokkaido University, N10W8, Kita-ku, Sapporo 060-0810, Japan; Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo 062-8517, Japan. Electronic address: tamotsu.hoshino@aist.go.jp.
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Hoshino
mesh_terms: D020418:Algal Proteins / Q000737:chemistry* / Q000302:isolation & purification; D000864:Antarctic Regions; D021301:Antifreeze Proteins / Q000737:chemistry* / Q000302:isolation & purification; D003460:Crystallization; D017377:Diatoms / Q000737:chemistry* / Q000502:physiology; D005615:Freezing; D005656:Fungal Proteins / Q000737:chemistry; D007053:Ice / Q000032:analysis*; D007700:Kinetics; D018716:Molecular Mimicry; D011485:Protein Binding
chemical_list: D020418:Algal Proteins; D021301:Antifreeze Proteins; D005656:Fungal Proteins; D007053:Ice
keywords: Adaptation; Alga; Basidiomycete; Environmental condition; Frost resistance