New Roles For Antifreeze Proteins

Researchers report for the first time that antifreeze proteins and glycoproteins—used up to now only to control ice crystal growth—can also control formation of other types of crystals, including those of carbohydrates. The antifreeze biomolecules work by binding to specific ice crystal faces that they resemble structurally. Sen Wang of Stanford University; Xin Wen of California State University, Los Angeles; and coworkers speculated that they might also work with the pyranose sugar methyl α-D-mannopyranoside (MDM), with which they are also structurally compatible. They show that MDM crystals grown in the presence of antifreeze proteins and glycoproteins are smaller, have better defined shapes, and have fewer crystal defects than those formed without antifreeze proteins and glycoproteins and that only tiny amounts (molar ratios as low as 10^–7) of the biomolecules are needed to control growth (J. Am. Chem. Soc. 2014, DOI: 10.1021/ja502837t). MDM crystals are widely used industrially in the synthesis of resins, plastics, and explosives. So using antifreeze proteins and glycoproteins to control crystal growth could be commercially useful, especially if the approach can also be extended to other industrially important crystals.