title: Binding of an oligopeptide to a specific plane of ice.
abstract: 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.
authors.affiliation: Protein Engineering Network of Centres of Excellence and the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
authors.forename: M E
authors.initials: ME
authors.lastname: Houston
authors.forename: H
authors.initials: H
authors.lastname: Chao
authors.forename: R S
authors.initials: RS
authors.lastname: Hodges
authors.forename: B D
authors.initials: BD
authors.lastname: Sykes
authors.forename: C M
authors.initials: CM
authors.lastname: Kay
authors.forename: F D
authors.initials: FD
authors.lastname: Sönnichsen
authors.forename: M C
authors.initials: MC
authors.lastname: Loewen
authors.forename: P L
authors.initials: PL
authors.lastname: Davies
mesh_terms: 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
chemical_list: D021301:Antifreeze Proteins; D006023:Glycoproteins; D007053:Ice; D009842:Oligopeptides