Effect of physicochemical conditions on the ultrafiltration of β-lactoglobulin

Fluorescence probing of induced structural changes

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This work aims for determining the impact of different environmental conditions, such as pH, ionic strength (salt concentration) and the chemistry of the membrane surface (hydrophilic/hydrophobic character) on the structure of permeating proteins after ultrafiltration. In the permeation experiments reported in this paper, different solutions of a model protein - β-lactoglobulin - at pH 3, 5 and 8 and salt concentrations of 1, 10 and 100 mM were processed with membranes of different molecular weight cut-off (10 and 30 kDa) and materials (regenerated cellulose-RC, and polyethersulfone-PES). The analysis of the structural alterations induced in the permeating molecules of β-lactoglobulin after ultrafiltration was performed using a methodology that combines the use of complementary fluorescence techniques: steady-state fluorescence and steady-state fluorescence anisotropy. From the results obtained it was concluded that permeation performed under pH values below the isoelectric point of β-lactoglobulin, at high salt concentrations and using membranes with hydrophobic character allows for minimization of the impact of the membrane processing in the structure of β-lactoglobulin.

Original languageEnglish
Pages (from-to)69-80
Number of pages12
JournalJournal of Membrane Science
Issue number1
Publication statusPublished - 1 Aug 2008



  • β-Lactoglobulin
  • Fluorescence
  • Membrane
  • Protein structure
  • Ultrafiltration

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