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Measurement of grain growth in the recrystallization of rapidly frozen solutions of antifreeze glycoproteins
Author(s) -
Yeh Y.,
Feeney R. E.,
McKown R. L.,
Warren C. J.
Publication year - 1994
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360341107
Subject(s) - recrystallization (geology) , activation energy , chemistry , supercooling , arrhenius equation , thermodynamics , crystallography , grain growth , analytical chemistry (journal) , chromatography , microstructure , paleontology , physics , biology
A quantitative estimate of the activation energy for grain growth has been obtained by analyzing ice recrystallization experiments from water and from solutions with small amounts (< 1.0 μg/mL) of antifreeze glycoprotein (AFGP). Rates of grain growth are measured as changes of grain diameter in time, with the supercooled holding temperature aVid glycoprotein concentration as parameters. Arrhenius plots of these rates vs (1/ T ) yielded slopes proportional to the activation energies for the particular species. The values of activation energy are almost independent of solution concentration or the species of AFGP. Averaged activation energy value for the AFGP‐4 species is Q g = (6.61 ± 1.02) × 10 5 J/mole. The “less active” AFGP‐8 yielded an average Q g = (5.71 ± 2.39) × 10 5 J/mole, quite similar to the AFGP‐4 species. The activation energy for recrystallization in a pure ice‐water system was estimated from two temperature points, T = −5.4 and −7.5°C. The best value is 2.39 × 10 5 J/mole, nearly twice that obtained by M. N. Martino and N. E. Zaritsky [(1989) Cryobiology , Vol. 26, p. 138] in a recrystallization experiment using salt solution, but much smaller than the values derived from the AFGP solutions. Results further show that activation entropy is at least a factor of 2 larger for the AFGP species than that of pure ice‐water system under the same growth conditions. These results suggest significant roles, both energetically and entropically, for AFGP molecules in their ability to inhibit grain growth of ice. © 1994 John Wiley & Sons, Inc.