1msi
From Proteopedia
STRUCTURE OF ANTIFREEZE GLYCOPROTEIN QAE(HPLC 12)
Overview
Antifreeze proteins (AFPs) have the unique ability to adsorb to ice and inhibit its growth. Many organisms ranging from fish to bacteria use AFPs to retard freezing or lessen the damage incurred upon freezing and thawing. The ice-binding mechanism of the long linear alpha-helical type I AFPs has been attributed to their regularly spaced polar residues matching the ice lattice along a pyramidal plane. In contrast, it is not known how globular antifreeze proteins such as type III AFP that lack repeating ice-binding residues bind to ice. Here we report the 1.25 A crystal structure of recombinant type III AFP (QAE isoform) from eel pout (Macrozoarces americanus), which reveals a remarkably flat amphipathic ice-binding site where five hydrogen-bonding atoms match two ranks of oxygens on the [1010] ice prism plane in the <0001> direction, giving high ice-binding affinity and specificity. This binding site, substantiated by the structures and properties of several ice-binding site mutants, suggests that the AFP occupies a niche in the ice surface in which it covers the basal plane while binding to the prism face.
About this Structure
1MSI is a Single protein structure of sequence from Macrozoarces americanus. Full crystallographic information is available from OCA.
Reference
Structural basis for the binding of a globular antifreeze protein to ice., Jia Z, DeLuca CI, Chao H, Davies PL, Nature. 1996 Nov 21;384(6606):285-8. PMID:8918883 Page seeded by OCA on Sat May 3 01:40:26 2008
