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Updated: Jun 17, 2026

Identification of Plant Ice-binding Proteins Through Assessment of Ice-recrystallization Inhibition and Isolation Using Ice-affinity Purification
Published on: May 5, 2017
Antifreeze protein in Antarctic marine diatom, Chaetoceros neogracile
In Gyu Gwak1, Woong Sic Jung, Hak Jun Kim
1Department of Life Science, Research Institute for Natural Sciences, Hanyang University, 133-791 Seoul, South Korea.
Abstract:
The antifreeze protein gene (Cn-AFP) from the Antarctic marine diatom, Chaetoceros neogracile was cloned and characterized. The full-length Cn-AFP cDNA contained an open reading frame of 849 bp and the deduced 282 amino acid peptide chain encodes a 29.2 kDa protein, which includes a signal peptide of 30 amino acids at the N terminus. Both the Cn-AFP coding region with and without the signal sequence were cloned and expressed in Escherichia coli. Recombinant Cn-AFPs were shown to display antifreeze activities based on measuring the thermal hysteresis and modified morphology of single ice crystals. Recombinant mature Cn-AFP showed 16-fold higher thermal hysteresis activity than that of pre-mature Cn-AFP at the same concentration. The ice crystal shape changed to an elongated hexagonal shape in the presence of the recombinant mature Cn-AFP, while single ice crystal showed a circular disk shape in absence of Cn-AFP. Northern analysis demonstrated a dramatic accumulation of Cn-AFP transcripts when the cells were subjected to freezing stress. This rapid response to freeze stress, and the antifreeze activity of recombinant Cn-AFPs, indicates that Cn-AFP plays an important role in low temperature adaptation.
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