Effects of surfactants on emulsification and secondary structure of lysozyme in aqueous solutions

This paper reports our investigations on the secondary structure of lysozym e in aqueous solution with D2O and comparing systems emulsified with ionic and non-ionic amphiphiles, respectively. The opposite effect of concentrati on of surfactants on the lysozyme aqueous system was studied and the activi ty of lysozyme by the turbidimetric assay with different kinds of surfactan t was compared. The effect of different surfactants on emulsification volum e formed was observed and discussed. The different interactive patterns bet ween lysozyme and ionic and non-ionic surfactants, such as sodium dodecyl s ulfate (SDS), cetyl trimethyl ammonium bromide (CTAB) and Triton-X100 (Isoo ctoylphenoxypolyethoxy ethanol), respectively, was studied with FTIR. A sim ple relationship between the secondary structure and denaturation of protei n is given for the emulsification of lysozyme in aqueous solutions. It is i mportant for understanding the stabilization and avoiding the emulsions in the extraction process that the interactions between the proteins and surfa ctants which leads to the formation of such complexes are characterized. Th e utility of surfactants as a de-emulsifying agent for the commercial proce ss to extract penicillin G from the filtrate of fermentation broth was cons istent with these results. (C) 1998 Elsevier Science S.A. All rights reserv ed.