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EFFECT OF SURFACTANT STRUCTURE AND PROPERTIES ON ENZYME-SURFACTANT INTERACATIONS Derek Kim1 and P. Somasundaran1 Department of Earth & Environmental Engineering1, Columbia University; New York, NY 10027 Objectives: Develop compatible enzyme-surfactant systems Challenges: Minimize enzyme function loss by modifying surfactant systems without sacrificing performance Correlate structure and properties of surfactants with their interactions with enzymes to predict compatibility Intellectual Motivation: Investigate impact of surfactant structure and properties on enzyme function (activity), structure (stability), and dynamics Industrial Relevance: Home and Personal Care, Cosmetics, Foods, Pharmaceuticals, Renewable Energy, Biotechnology, Bioremediation Broad Appeal: Enzyme-Surfactant Formulations, Enzyme Activity/Stability, Colloidal Interactions, Mixed Surfactants Materials / Methods Background / Problem Enzymes: protease (positive charge), peroxidase (neutral charge) • Enzymes increasingly used with surfactants in industries Surfactants: anionic (SDS) / nonionic (AE, DM, APG) Properties • Enzyme activity lost in oppositely charged surfactants – (aggregation, micellization, charge) of enzyme-surfactant unfolding / denaturation occurs mainly due to: colloidal systems surface tension, DLS, electrostatic repulsion of charges of bound pyrene fluorescence Structure and dynamics of enzyme surfactants Enzyme activities with with addition of surfactants – surfactants –Activity assays with spectroscopy stability/mobility – penetration of surfactant hydrocarbon chain into S.S., time resolved fluorescence nonpolar regions of protein Understand mechanisms of interactions between enzymes and surfactants • • • Summary 1. Ionic surfactant – Enzyme activity suppressed by surfactant monomers 2. Nonionic surfactant – Enzyme activity unchanged and even enhanced at surfactant concentrations where loosely packed micelles are formed → Disorder in water structure → Greater enzyme flexibility → Higher activity 3. Mixed ionic-nonionic surfactant – Enzyme activity loss lessened compared to single anionic surfactants Hydrophobic interactions Electrostatic interactions Conformational change in protein structure Results Protease Activity Change with Addition of Anionic and Mixed Surfactants Hypothesis Interactions between an enzyme and mixed surfactant system will be strongly dictated by the ability of nonionic surfactant to form mixed micelles with ionic surfactant and inhibit electrostatic interactions 0 0 ‐5 ‐5 ‐10 ‐10 % Change in ‐15 Rate Constant % Change in ‐15 Rate Constant ‐20 ‐20 ‐25 ‐25 ‐30 ‐30 1 mM SDS 5 mM SDS 7.5 mM SDS 1 mM 1:1 SDS+AE 5 mM 1:1 SDS+AE 10 mM SDS 20 mM SDS 200 mM SDS 7.5 mM 1:1 SDS+AE 10 mM 1:1 SDS+AE 20 mM 1:1 SDS+AE Future Plans 1. Investigate enzyme activity changes with various surfactant systems 2. Investigate effects of surfactant properties on enzyme structure and function and evaluate interaction mechanisms 3. Examine enzyme structural and dynamic changes with addition of surfactants Acknowledgement: This material is based upon work supported the National Science Foundation under Grant No. 1362060 and by CPaSS industry members. Fall 2016 IAB Meeting – August 10-11, 2016