Effects of mechanical agitation, heating and pH on the structure of bovine alpha lactalbumin
1997
Dhanapati, N. (College of Dairying, Ebetsu, Hokkaido (Japan)) | Ishioroshi, M. | Yoshida, I. | Samejima, K.
Functional properties of bovine alpha lactalbumin (alpha-LA) are related to its structure and are governed by changes in conformation of protein molecules. The effects of mechanical agitation, high temperature and pH on the structural changes of alpha-LA were examined by circular dichroism (CD), differential scanning calorimetry (DSC), spectrofluorometry, spectrophotometry, and electrical conductivity methods. The alpha-helix content decreased significantly below pH 5 and above pH 10. The transition enthalpy values at pH 2, 6.7 and 12 were 91.5, 111.6 and 100.3 J/g, respectively. Heating alpha-LA from 60 to 100 degrees C at pH 6.7, resulted in the increase of absorbance and electrical conductivity and the decrease in fluorescence intensity. Higher speed agitation decreased the alpha-helix content considerably. It is concluded that alpha-LA undergoes a conformational change due to strong acid and alkaline pHs, high temperatures and strong agitation
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