Biomaterial Database

Valine substituted winter flounder 'antifreeze': preservation of ice growth hysteresis. 1998

A D Haymet, and L G Ward, and M M Harding, and C A Knight

Department of Chemistry, University of Houston, TX 77204-5641, USA. haymet@uh.edu

Three mutant polypeptides of the type I 37-residue winter flounder 'antifreeze' protein have been synthesized. All four threonine residues in the native peptide were been mutated to serine, valine and glycine respectively and two additional salt bridges were incorporated into the sequences in order to improve aqueous solubility. The peptides were analyzed by nanoliter osmometry, the 'ice hemisphere' test, the 'crystal habit' test, measurement of ice growth hysteresis and CD spectroscopy. While the valine and serine mutants retain the alpha-helical structure, only the valine mutant retains 'antifreeze' activity similar to that of the native protein. These data show that the threonine hydroxyl groups do not play a crucial role in the accumulation of the native 'antifreeze' protein at the ice/water interface and the inhibition of ice growth below the equilibrium melting temperature.

UI	MeSH Term	Description	Entries
D007053	Ice	The solid substance formed by the FREEZING of water.
D010455	Peptides	Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are considered to be larger versions of peptides that can form into complex structures such as ENZYMES and RECEPTORS.	Peptide,Polypeptide,Polypeptides
D002942	Circular Dichroism	A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Circular Dichroism, Vibrational,Dichroism, Circular,Vibrational Circular Dichroism
D005432	Flounder	Common name for two families of FLATFISHES belonging to the order Pleuronectiformes: left-eye flounders (Bothidae) and right-eye flounders (Pleuronectidae). The latter is more commonly used in research.	Plaice,Platichthys,Pleuronectes,Pseudopleuronectes,Halibut,Pleuronectes platessa,Flounders
D006023	Glycoproteins	Conjugated protein-carbohydrate compounds including MUCINS; mucoid, and AMYLOID glycoproteins.	C-Glycosylated Proteins,Glycosylated Protein,Glycosylated Proteins,N-Glycosylated Proteins,O-Glycosylated Proteins,Glycoprotein,Neoglycoproteins,Protein, Glycosylated,Proteins, C-Glycosylated,Proteins, Glycosylated,Proteins, N-Glycosylated,Proteins, O-Glycosylated
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013912	Threonine	An essential amino acid occurring naturally in the L-form, which is the active form. It is found in eggs, milk, gelatin, and other proteins.	L-Threonine,L Threonine
D014633	Valine	A branched-chain essential amino acid that has stimulant activity. It promotes muscle growth and tissue repair. It is a precursor in the penicillin biosynthetic pathway.	L-Valine,L Valine
D019943	Amino Acid Substitution	The naturally occurring or experimentally induced replacement of one or more AMINO ACIDS in a protein with another. If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish, enhance, or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties.	Amino Acid Substitutions,Substitution, Amino Acid,Substitutions, Amino Acid
D021301	Antifreeze Proteins	Proteins that bind to ice and modify the growth of ice crystals. They perform a cryoprotective role in a variety of organisms.	Antifreeze Glycopeptide,Antifreeze Glycoprotein,Antifreeze Glycoproteins,Antifreeze Peptide,Antifreeze Protein,Thermal Hysteresis Protein,AFGP,Antifreeze Glycopeptides,Antifreeze Peptides,Thermal Hysteresis Proteins,Glycopeptide, Antifreeze,Glycopeptides, Antifreeze,Glycoprotein, Antifreeze,Glycoproteins, Antifreeze,Hysteresis Protein, Thermal,Hysteresis Proteins, Thermal,Peptide, Antifreeze,Peptides, Antifreeze,Protein, Antifreeze,Protein, Thermal Hysteresis,Proteins, Antifreeze,Proteins, Thermal Hysteresis