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Two-Dimensional Analysis Of Skim Milk Proteins Using Preparative Isoelectric Focusing Followed By Polyacrylamide Gel Electrophoresis, Hye-Hyun Y. Kim, Rafael Jiménez-Flores

Dairy Science

A preparative isoelectric focusing (IEF) method was applied to separate skim milk proteins using the Rotofor device in a pH 3-10 gradient containing 4 M urea/1% triton X-100. Each of the 20 fractions obtained from the Rotofor device was then analyzed by polyacrylamide gel electrophoresis (PAGE). Both urea-PAGE and SDS-PAGE were used to separate purified caseins and skim milk resulting in comparable two-dimensional pattern. The major bovine caseins (α_s1, α_s2, β, κ-casein) were resolved better on urea-PAGE. The α_s1- and β -casein were focused at pH ~ 4.5 and 4.8, respectively, whereas α_{s2 …}