When Enzymes And Green Surfactants Meet

Surfactants and proteins coexist in many different industries, ranging from detergents to pharmaceutics. Surfactant-protein interactions are multi-faceted and can range from limited interactions, as typically observed with nonionic surfactants, to complete denaturation of the protein, more typical of anionic surfactants such as sodium dodecyl sulphate (SDS). Denaturation of proteins and enzymes can be driven by both monomeric and micellar surfactant interactions [1].Biosurfactants are produced by microorganisms and have promising properties. They have strong interfacial properties [2] that are promising for industrial use. Despite growing interest, their impact on protein and enzyme stability remains at an early stage of investigation. Studies with model proteins suggest a relatively mild interaction with slow inactivation kinetics [3]. Membrane proteins can be refolded in their presence [4].Here we report interactions between industrial/detergent enzymes and two glycolipid-biosurfactants: Anionic rhamnolipid (RL) produced in Pseudomonas aeruginosa and mixed anionic/nonionic sophorolipid (SL) produced in Candida bombicola. RL and SL both act as mild biosurfactants that despite their anionic charge are compatible with industrial enzymes. The lipase from Thermomyces lanuginosus (TlL) shows pH dependent interactions. At pH 8 we do not detect interactions between TlL and RL or SL, with only minor perturbations to stability and activity. However, lowering pH from 8 to 6 favor stronger interactions between TlL and RL/SL that strongly stabilizes TlL and opens the active site with a 3- to 6-fold boost to activity. We use SAXS to qualitatively determine formation of complexes between TlL and SL and RL micelles at pH 6.1.Otzen, D.E., P. Sehgal, and P. Westh. J Colloid Interface Sci, 2009.329(2): p.273-83.2.Nguyen, T.T. and D.A. Sabatini. Int J Mol Sci, 2011.12(2): p.1232-44.3.Andersen, K.K. and D.E. Otzen. Biochim Biophys Acta, 2014.1844: p.2338-2345.4.Andersen, K.K. and D.E. Otzen. FEBS Lett, 2014.588: p.1955-60.