The asymmetric unit comprises two RiAFP molecules juxtaposed with their ice-binding surfaces, however the protein is monomer in the solutio
Overall Structure
The crystallographic structure of RiAFP was defined recently[1]. It reveals a new β-solenoid architecture that forms of of remarkable regularity. The β-sheets lie on top of each other with the upper and lower strands parallel but in the opposite orientation. Two ends deviate from β helix regularity by forming . These capping structures help to prevent end-to-end associations that would spoil the solubility of RiAFP and lead to oligomerization and aggregation.
The three residues in β-strand 11 at the C terminus that are too bulky to be accommodated into the core may also contribute to the capping structure to prevent amyloid-like polymerization. RiAFP solenoid possesses compressed nature. In the core of RiAFP, the side chains within apposed β-strands from the two β-sheets are staggered, allowing the side chains to interdigitate and pack tightly against one another. Most of the in the core are from Ala, Ser and Thr. Those residues create a more compact fold that may contribute to the high stability and antifreeze activity of RiAFP. Within the core there are between Thr-Ser (65-55, 85-75, 132-124 respectively) and one between Cys4-Cys21, that contributes to stabilization of the whole structure. The β-turns in the structure contain mostly Gly or Pro residues.
Ice Binding Surface (IBS)
Function
Disease
Relevance
Structural highlights
