Interfacial Enzymes and Their Interactions with Surfaces: Nathalie Willems, Mickae¨l Lelimousin, Heidi Koldsø,

Enzymes that function at an interface (i.e., interfacial enzymes) actin biological processes as diverse as cell signaling and transduction,membrane remodeling, digestion, endocytosis, and inflammation[1]. Indeed almost half the proteins in a cell may exhibit a degreeof association with membranes and, therefore, must work at aninterface [2]. Interfaces can include the cellular membrane environ-ment, intowhich nonpolar enzymatic substrates can partition, or theaggregation of nonpolar substrates that formmicelle-like structures,liposomal dispersions, or emulsions [3, 4]. Interfacial enzymes haveevolved to function within the physical constraints imposed bysuch an environment, including effects on substrate accessibility,enzyme orientation, partitioning, and the equilibrium betweenassociated and dissociated states [4]. These processes ultimatelygovern the kinetics of the catalyzed reaction and determine theconditions essential for the normal functioning of biologicallyimportant processes. These dynamic processes are significant inunderstanding the cell biology of membranes and the intracellularenvironment and are also of biotechnological relevance. Interfacialenzymes have considerable potential for industrial applications,such as lipases in food, detergent, and related industries. Forexample, Candida antartica lipase B is commercially available as an immobilized enzyme in laundry detergent [5]. However,fuller exploitation of interfacial enzymes remains limited by ourincomplete molecular understanding of the underlying dynamicenzymatic mechanism.