Binding of an oligopeptide to a specific plane of ice.
The alpha-helical antifreeze protein (AFP) from winter flounder inhibits ice growth by binding to a specific set of pyramidal surface planes that are not otherwise macroscopically expressed. The 37-residue AFP contains three 11-amino acid repeats that make a stereo-specific fit to the ice lattice along the <01-12> direction of the (20-21) and equivalent binding planes. When the AFP was shortened to delete two of the three 11-amino acid ice-binding repeats, the resulting 15-residue peptide and its variants were less helical and showed no antifreeze activity. However, when the helicity of the peptide was reinforced by an internal lactam bridge between Glu-7 and Lys-11, the minimized AFP was able to stably express the pyramidal plane (20-21) on the surface of growing ice crystals. This dynamic shaping of the ice surface by a single ice-binding repeat provides evidence that AFP adsorption to the ice lattice is not an "all-or-nothing" interaction. Instead, a partial interaction can help develop the binding site on ice to which the remainder of the AFP (or other AFP molecules) can orient and bind.
Houston
M E
ME
Protein Engineering Network of Centres of Excellence and the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
Chao
H
H
Hodges
R S
RS
Sykes
B D
BD
Kay
C M
CM
Sönnichsen
F D
FD
Loewen
M C
MC
Davies
P L
PL
D021301:Antifreeze Proteins; D002942:Circular Dichroism; D003461:Crystallography; D006023:Glycoproteins / Q000737:chemistry*; D006358:Hot Temperature; D007053:Ice; D009842:Oligopeptides / Q000737:chemistry*; D011489:Protein Denaturation; D017433:Protein Structure, Secondary
D021301:Antifreeze Proteins; D006023:Glycoproteins; D007053:Ice; D009842:Oligopeptides