Calorimetric analysis of antifreeze glycoproteins of the polar fish, Dissostichus mawsoni.
Solutions of antifreeze glycoproteins 1 through 5 and 8 were analyzed for activity by differential scanning calorimetry. With a scan rate of 1 degree C min-1, antifreeze glycoproteins 1-5 (20 mg/ml) revealed antifreeze activity with a delay in the freeze exotherm during cooling in the presence of ice. Antifreeze glycoprotein 8 (60 mg/ml), however, did not reveal antifreeze activity. When a 0.1 degree C min-1 scan rate was used, glycoproteins 1-5 again yielded a delay in the freeze onset, but the exotherm consisted of multiple events. At the slower scan glycoprotein 8 revealed an initial freeze followed by multiple exothermic events resembling those of glycoproteins 1-5. Thermograms exhibiting antifreeze activity had an initial shoulder in the exotherm direction upon cooling followed by a delay before the exotherm. The shoulders were correlated with c-axis ice growth observed in visual methods. The glycoprotein antifreezes had a linear increase in activity with decreased ice content.
Hansen
T N
TN
Center for Cryobiological Research, SUNY-Binghamton 13901.
DeVries
A L
AL
Baust
J G
JG
D000818:Animals; D021301:Antifreeze Proteins; D002152:Calorimetry, Differential Scanning; D003081:Cold Climate; D005399:Fishes / Q000378:metabolism*; D005615:Freezing; D006023:Glycoproteins / Q000032:analysis*; D013696:Temperature
D021301:Antifreeze Proteins; D006023:Glycoproteins