TAILIEUCHUNG - Báo cáo khoa học: Effect of annealing time of an ice crystal on the activity of type III antifreeze protein

Antifreeze proteins (AFPs) possess a unique ability to bind to a seed ice crystal to inhibit its growth. The strength of this binding has been evalu-ated by thermal hysteresis (TH). In this study, we examined the dependence of TH on experimental parameters, including cooling rate, annealing time, annealing temperature and the size of the seed ice crystal for an isoform of type III AFP from notched-fin eelpout (nfeAFP8). | ỊFEBS Journal Effect of annealing time of an ice crystal on the activity of type III antifreeze protein Manabu Takamichi1 2 Yoshiyuki Nishimiya1 Ai Miura1 and Sakae Tsuda1 2 1 FunctionalProtein Research Group Research Institute of Genome-based Biofactory National institute of Advanced Industrial science and Technology AIST Toyohira Sapporo Japan 2 Division of BiologicalSciences Graduate Schoolof Science Hokkaido University Kita Sapporo Japan Keywords adsorption-inhibition annealing time notched-fin eelpout thermal hysteresis type III antifreeze protein Correspondence S. Tsuda FunctionalProtein Research Group Research Institute of Genome-based Biofactory NationalInstitute of Advanced IndustrialScience and Technology AIST 2-17-2-1 Tsukisamu-Higashi Sapporo 062-8517 Japan Fax 81 11 857 8983 Tel 81 11 857 8912 E-mail Website http rigb fprg Received 26 July 2007 revised 29 September 2007 accepted 24 October 2007 Antifreeze proteins AFPs possess a unique ability to bind to a seed ice crystal to inhibit its growth. The strength of this binding has been evaluated by thermal hysteresis TH . In this study we examined the dependence of TH on experimental parameters including cooling rate annealing time annealing temperature and the size of the seed ice crystal for an isoform of type III AFP from notched-fin eelpout nfeAFP8 . TH of nfeAFP8 dramatically decreased when using a fast cooling rate C-min-1 . It also decreased with increasing seed crystal size under a slow cooling rate oC-min_1 but such dependence was not detected under the fast cooling rate. TH was enhanced and when ice crystals were annealed for 3 h at and C below Tm respectively. After annealing for 2 h at C below Tm TH activity showed marked dependence on the size of ice crystals. These results suggest that annealing of an ice crystal for 2-3 h significantly increased the TH value of type III AFP. Based on a proposed .

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