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Effects of Chemical Modification and Sodium Dodecyl Sulphate Binding on the Thermostability of Whey Proteins

M. Donovan and D. M. Mulvihill
Irish Journal of Food Science and Technology
Vol. 11, No. 1 (1987), pp. 77-85
Stable URL: http://www.jstor.org/stable/25558154
Page Count: 9
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Effects of Chemical Modification and Sodium Dodecyl Sulphate Binding on the Thermostability of Whey Proteins
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Abstract

The effects of addition of sodium dodecyl sulphate (SDS), potassium iodate (KIO₃) and N-ethylmaleimide (NEM) to rennet casein whey on the overall thermostability of the whey proteins were investigated. The addition of SDS at concentrations of 0.1 to 0.5% (w/v) caused marked thermal stabilization of the proteins at the expense of concentration-dependent pre-thermal SDS-induced structural modifications. β-Lactoglobulin was the only whey protein altered electrophoretically on the addition of KIO₃ (5 mM) to whey at room temperature and it and α-lactalbumin were stabilized against thermal changes by KIO₃ addition to whey at pH 6.7 while bovine serum albumin was not stabilized. On addition of KIO₃ to whey at pH 5.1 α-lactalbumin was again thermally stabilized while β-lactoglobulin was made more thermo-sensitive at this pH. The thiol blocking agent N-ethylmaleimide altered the electrophoretic mobility of β-lactlglobulin and made it more thermo-resistant at pH 6.7, however, it did not have the same thermal protective effect at pH 5.1, either because disulphide aggregation reactions are not as important for the thermal aggregation of β-lactoglobulin at this pH or N-ethylmaleimide is not as effective a blocking agent at low pH.

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