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24, chemin de Borde Rouge –Auzeville – CS52627
31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

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Internet de l'unité STLO Science et Technologie du Lait et de l'Oeuf

STLO Research Unit

Managing protein membrane separation

Membrane filtration pilot
Membrane technologies (ultrafiltration, microfiltration and nanofiltration) have revolutionised the industry and multiplied the use of milk as an ingredient. Improving and modelling these processes from a sustainable perspective is a primary field of research at the STLO Unit

The impact of membrane filtration on the final properties of proteins must be clarified, especially in the case of metalloproteins. Considering α-lactalbumin (α-LA), the role of its cofactor Ca2+ is predominant in controlling the final quality of protein fractions since it guarantees structure, bioactivity and stability of the protein.

 Equilibrium between the holo-form and the apo-form of α-lactalbumin (α-LA).

Holo- and apo-alpha-lactalbumin


We confirmed, for the first time, that protein conformation impacts ultrafiltration performances of metalloproteins:

  • Transmission of the calcium-depleted form (apo-α-LA) is higher than the native form (holo). Selectivity is presumably due to distinct flexibility and/or surface hydrophobicity between protein conformations.
  • Within a mixture, the higher transfer of apo-α-LA displaces the equilibrium between Ca2+ and the protein. This displacement tends to increase the Ca2+/α-LA molar ratio similar to the holo-α-LA in permeate.


Ultrafiltration can be an alternative to chromatography for the fractionation of metalloproteins.It offers high selectivity and is attractive from environmental and economic perspectives.





This study was financed by the French National Research Agency, project Ecoprom, ANR-06-PNRA-015.


Read more

Van Audenhaege M., Pezennec S., Gesan-Guiziou G. (2013). Ultrafiltration membrane cut-off impacts structure and functional properties of transmitted proteins: Case study of the metalloprotein α-lactalbumin. Separation and Purification Technology 114: 73-82.

Van Audenhaege M., Lambrouin F., Piot M., Gesan-Guiziou G. (2012). Unexpected displacement of the equilibrium between the apo and the holo form during ultrafiltration of the metalloprotein alpha-lactalbumin. Journal of Membrane Science 401-402: 195-203.

Belmejdoub J., Rabiller-Baudry M., Delaunay D., Gesan-Guiziou G. (2012). Structural modifications of globular proteins in an ultrafiltration loop as evidenced by intrinsic fluorescence and reverse-phase liquid chromatography.Separation and Purification Technology 96:274-288.



Geneviève Gésan-Guiziou • Scientist in Tipil team

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