Abhiram Arunkumar - Fractionation of alpha-lactalbumin from beta-lactoglobulin using positively charged tangential flow ultrafiltration membranes

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  Publication Details (including relevant citation   information):

  A. Arunkumar, M.R. Etzel (2013), Sep. Purif. Technol., 105, 121


  1.         The fractionation of the dairy proteins, a-lactalbumin     (ALA) and b-lactoglobulin     (BLG),
        was examined using tangential flow ultrafiltration. ALA and BLG     differ somewhat
        in isoelectric point (4.4 vs. 5.2, respectively), but not in     size (14.4 kDa vs.
        18.4 kDa, respectively). By placing a positive charge on a 300     kDa composite
        regenerated cellulose membrane and adjusting the solution pH     and ionic
        strength, nearly 490% increase in selectivity for the     fractionation of ALA from
        a binary solution containing ALA and BLG was observed, compared     to the
        uncharged membrane. Thus, like-sized proteins that differ only     somewhat in
        isoelectric point, and that are about 15-20 times smaller than     the membrane
        molecular-weight cutoff (MWCO) are fractionated using charged     ultrafiltration
        membranes. A binary solution containing a 50:50 mixture of ALA     and BLG was used
        to obtain 87% pure ALA using a two-stage flow configuration. A     mass balance
        model for the fractionation of proteins using membranes in     staged
        configurations was developed and it compared well with     experimental
        observations. This work demonstrates that chromatographic     purity can be
        obtained in the fractionation of proteins without the use of     chromatography by
        placing a charge on the ultrafiltration membrane and using it     in a staged

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