加熱中のカゼインの高次構造の変化と冷却による復元

概要

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Reversible transconformation of casein induced by heating at temperature from 15°C to 70°C and cooling to 15°C was studied using ultraviolet difference absorption spectra and pH measurement. (1) Difference spectra of whole casein solution showed hyperchromisity (240_??_260 mμ and 283_??_310 mμ) and hypochromisity (260_??_283 mμ) resulting from red shift of absorption spectra which altered by the change of temperature. The difference spectra had 2 characteristic peaks at 287_??_288 mμ, due to tyrosine side chain, and 293_??_294 mμ, due to tryptophan side chain, which grew up with elevated temperature up to 70°C and disappeared after cooling. (2) When κ-casein was heated at 60°C, light dispersion was caused by aggregation. After cooling casein solution became clear again. (3) pH value of casein solution was changed by heating from pH 6.75 at 10°C to pH 6.54 at 50°C and pH 6.57 at 60°C, and by cooling from pH 6.59 at 60°C to pH 6.85 at 25°C and pH 6.76 at 10°C. These results suggest reversible transconformation of casein at elevated temperature.
社団法人日本農芸化学会の論文