Cooperative functioning between antifreeze glycoproteins.

Antifreeze glycoproteins from polar fish bloods are a mixture of closely related components which differ structurally by size and by the presence of proline in the smaller components. Although the smaller components containing proline exist in higher amounts than do the larger ones, their presence puzzled investigators because they had very weak antifreeze activity. A very important function for these smaller components has now been found. These smaller antifreeze glycoproteins (10 to 25 mg/ml) have now been tested as mixtures with the larger active antifreeze glycoproteins (2 to 4 mg/ml) and a very large (2- to 8-fold) potentiation of antifreeze activity has been observed. There appears to be a cooperative functioning between the larger and smaller components.