Biomaterial Database

Structure-function relationships in an antifreeze polypeptide. The role of charged amino acids. 1993

D Wen, and R A Laursen

Department of Chemistry, Boston University, Massachusetts 02215.

Several analogs of an alanine-rich alpha-helical antifreeze polypeptide were synthesized and studied to evaluate the role of charged amino acids on structure and activity. alpha-Helix content and thermal stability were assessed by circular dichroism spectrometry and antifreeze activity by freezing point depression (thermal hysteresis) and ice crystal growth rate measurements. Rearrangement, deletion and replacement of charged amino acids resulted in reduced helicity and antifreeze activity in some cases, but the effects were not dramatic. We conclude that the i+4 ion pair Lys18/Glu22 helps to stabilize the alpha-helix but is not absolutely essential for activity. NH2-terminal Asp does not contribute significantly to helix stability or activity, but the COOH terminus is sensitive to modification, since replacement of Arg37 can lead to reduced helix content and activity. In general, factors which reduce alpha-helix content also reduce antifreeze activity.

UI	MeSH Term	Description	Entries
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D004563	Electrochemistry	The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.	Electrochemistries
D005615	Freezing	Liquids transforming into solids by the removal of heat.	Melting
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
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000596	Amino Acids	Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.	Amino Acid,Acid, Amino,Acids, Amino
D013329	Structure-Activity Relationship	The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.	Relationship, Structure-Activity,Relationships, Structure-Activity,Structure Activity Relationship,Structure-Activity Relationships
D013816	Thermodynamics	A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)	Thermodynamic
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