Crystal structure of an antifreeze polypeptide and its mechanistic implications.
The X-ray crystallographic structure of an antifreeze polypeptide from the fish winter flounder, has been determined at 2.5 A by an analysis of the Patterson function. This is the first report of a polypeptide of this size that is a single alpha-helix. A proposed mechanism of antifreeze binding to ice surfaces is given which requires: first, that the dipole moment from the helical structure dictates the preferential alignment of the peptide to the c-axis of ice nuclei; second, amphiphilicity of the helix; and third, torsional freedom of the side chains to facilitate hydrogen bonding to ice surfaces.
Yang
D S
DS
Biocrystallography Laboratory, VA Medical Center, Pittsburgh, Pennsylvania 15240.
Sax
M
M
Chakrabartty
A
A
Hew
C L
CL
D000595:Amino Acid Sequence; D000818:Animals; D021301:Antifreeze Proteins; D005399:Fishes / Q000502:physiology*; D005412:Flatfishes / Q000502:physiology*; D005432:Flounder / Q000502:physiology*; D006023:Glycoproteins / Q000502:physiology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D013045:Species Specificity; D014961:X-Ray Diffraction
D021301:Antifreeze Proteins; D006023:Glycoproteins