Freezing behavior of fish blood glycoproteins with antifreeze properties

The blood of some species of antarctic fishes has previously been shown to contain freezing point-depressing glycoproteins, ranging in MW from 3,000 to 34,000 daltons. In aqueous solutions undergoing freezing, the glycoproteins are incorporated into the ice in a concentration identical to that in the liquid. The freezing point depression (fpd) appears to be related to the size of the glycoprotein, and for the smaller sizes, is also dependent on the rate of freezing. Supercooling of the serum is the presence of an ice seed has also been observed. These data indicate that the fpd caused by the glycoproteins is a noncolligative property. A mechanism for the fpd involving surface effects on ice is suggested.