Calorimetric determination of inhibition of ice crystal growth by antifreeze protein in hydroxyethyl starch solutions.
Differential scanning calorimetry and cryomicroscopy were used to investigate the effects of type I antifreeze protein (AFP) from winter flounder on 58% solutions of hydroxyethyl starch. The glass, devitrification, and melt transitions noted during rewarming were unaffected by 100 micrograms/ml AFP. Isothermal annealing experiments were undertaken to detect the effects of AFP-induced inhibition of ice crystal growth using calorimetry. A premelt endothermic peak was detected during warming after the annealing procedure. Increasing the duration or the temperature of the annealing for the temperature range from -28 and -18 degrees C resulted in a gradual increase in the enthalpy of the premelt endotherm. This transition was unaffected by 100 micrograms/ml AFP. Annealing between -18 and -10 degrees C resulted in a gradual decrease in the premelt peak enthalpy. This process was inhibited by 100 micrograms/ml AFP. Cryomicroscopic examination of the samples revealed that AFP inhibited ice recrystallization during isothermal annealing at -10 degrees C. Annealing at lower temperatures resulted in minimal ice recrystallization and no visible effect of AFP. Thus, the 100 micrograms/ml AFP to have a detectable influence on thermal events in the calorimeter, conditions must be used that result in significant ice growth without AFP and visible inhibition of this process by AFP.
Hansen
T N
TN
Cryolife, Incorporated, Marietta, Georgia 30067.
Carpenter
J F
JF
D000818:Animals; D021301:Antifreeze Proteins; D002152:Calorimetry, Differential Scanning / Q000379:methods; D005432:Flounder; D005615:Freezing; D005813:Genes, Synthetic; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D006895:Hydroxyethyl Starch Derivatives; D007053:Ice; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012996:Solutions
D021301:Antifreeze Proteins; D006023:Glycoproteins; D006895:Hydroxyethyl Starch Derivatives; D007053:Ice; D011994:Recombinant Proteins; D012996:Solutions