RÉSUMÉ

An atmospheric pressure, room temperature (18-25 °C) gas discharge process has been investigated for its ability to elicit protein covalent cross-linking leading to oligomers. A practical application of such technique is to improve the stability of heat sensitive proteins of medical interest. A non-thermal plasma can be produced in transient filamentary discharge channels taking place in an atmospheric pressure dielectric barrier discharge reactor. The proteins are submitted to the discharge reactor effluents in an aqueous solution, consisting of lysozyme (14 kD) aqueous solutions (25 mg/ml). The protein solution is split up into 10 μl droplets deposited on a target surface in order to increase the gas/liquid exchange surface. After the plasma treatment, the proteins cross-linking reaction was ascertained by the visualization of protein bands on SDS-polyacrylamide gels corresponding to dimers (28 kD) and trimers (42 kD) of lysozyme. The intermolecular bonds were found to be covalent since the same migration bands were obtained in drastic denaturing conditions (disrupting hydrogen and Van der Waals intermolecular bonds). Under specific operating conditions, approximately 20 % of the total protein present is converted into dimers and trimers after only 5 minutes treatment. The influence, on the cross-linking efficiency, of different parameters (feed gas composition, exposure duration and solution composition) is discussed in the paper. First results suggest a possible biological activity of the cross-linked dimers.