Ice-binding structure and mechanism of an antifreeze protein from winter flounder

• Published in: Nature (London) 1995-06, Vol.375 (6530), p.427-431
• Main Authors: Sicheri, F, Yang, D. S. C
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Antifreeze Proteins; Biochemistry; Biological and medical sciences; Computer Graphics; Crystalline structure; Crystallography, X-Ray; Crystals; Fish; Flounder; Freezing; Fundamental and applied biological sciences. Psychology; Glycoproteins - chemistry; Humanities and Social Sciences; Ice; letter; Marine; Molecular biophysics; Molecular Sequence Data; multidisciplinary; Pleuronectes americanus; Pleuronectiformes; Polar environments; Protein Binding; Protein Conformation; Proteins; Science; Science (multidisciplinary); Structure in molecular biology
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/375427a0

ANTIFREEZE proteins provide fish with protection against the freezing effect of polar environments by binding to ice surfaces and inhibiting growth of ice crystals. We present the X-ray crystal structure at 1.5 Å resolution of a lone α-helical antifreeze protein from winter flounder, which provides a detailed look at its icebinding features. These consist of four repeated ice-binding motifs, the side chains of which are inherently rigid or restrained by pair-wise side-chain interactions to form a flat binding surface. Elaborate amino- and carboxy-terminal cap structures are also present, which explain the protein's rich α-helical content in solution. We propose an ice-binding model that accounts for the binding specificity of the antifreeze protein along the axes of the {202¯1} ice planes 1 .