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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