Why ice-binding type I antifreeze protein acts as a gas hydrate crystal inhibitor

Antifreeze proteins (AFPs) prevent ice growth by binding to a specific ice plane. Some AFPs have been found to inhibit the formation of gas hydrates which are a serious safety and operational challenge for the oil and gas industry. Molecular dynamics simulations are used to determine the mechanism of action of the winter flounder AFP (wf-AFP) in inhibiting methane hydrate growth. The wf-AFP adsorbs onto the methane hydrate surface via cooperative binding of a set of hydrophobic methyl pendant groups to the empty half-cages at the hydrate/water interface. Each binding set is composed of the methyl side chain of threonine and two alanine residues, four and seven places further down in the sequence of the protein. Understanding the principle of action of AFPs can lead to the rational design of green hydrate inhibitor molecules with potential superior performance.