Hydrophobic interaction of lysozyme and alpha-lactalbumin from equine milk whey. |
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Authors: | P Haezebrouck W Noppe H Van Dael I Hanssens |
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Institution: | Interdisciplinary Research Center, K.U.L. Campus Kortrijk, Belgium. |
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Abstract: | From fluorescence measurements on mixtures of bis-ANS and equine lysozyme and from Ca(2+)-dependent hydrophobic interaction chromatography of equine lysozyme, it is demonstrated that Ca2+ binding induces a conformational change upon which hydrophobic regions in the protein become less accessible. Bis-ANS fluorescence titrations in the absence of Ca2+ and in 2 mM Ca2+ are also performed with equine alpha-lactalbumin variants B and C. These variants differ by an amino-acid exchange Asp----Ile at residue 95. The fluorescence titration curves indicate that the accessibility of the probe to the Ca2+ conformers is clearly influenced by the mutation. The Ca(2+)-dependent exclusion of a hydrophobic domain is used in a new and simplified method for preparing lysozyme and alpha-lactalbumins simultaneously from equine milk whey. |
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