Interaction of Glycolipid Biosurfactants with Model Membranes and Proteins

Abstract

Glycolipid biosurfactants formed by a fatty acid portion linked to a carbohydrate moiety display very interesting physicochemical, physiological, and biological properties. The most relevant glycolipid are rhamnolipids, trehalose lipids, and sophorolipids. The molecular mechanisms underlying the biological effects of these biosurfactants are not completely understood, but the amphiphilic and surface-active properties of glycolipid biosurfactants point to the interaction with cellular membranes where the modification of the membrane structure might affect the function of the cell. Many studies on the interaction between glycolipid biosurfactants and phospholipid model membranes have been carried out to get insight into the molecular mechanism of the biosurfactant-membrane interaction. The use of a great variety of experimental techniques allowed researchers to obtain information regarding the effect of these biosurfactants on the thermotropic gel to liquid crystalline and lamellar to non-lamellar phase transitions of phospholipids, to determine the thermodynamics of these interactions, and to obtain information on the organization and packing characteristics of the phospholipid bilayer together with fluidity, order, permeability, and hydration properties of the membrane. The results obtained from these works have given us a general molecular picture of the interaction between the biosurfactants and the membrane. On the light of the wide application of surfactant/protein systems in laboratory and in food, cosmetic and pharmaceutical industries, the study of the interaction between glycolipid biosurfactants and proteins have attracted the attention of several researchers. A few studies using different techniques have provided information about binding of biosurfactants to proteins and their effects on enzyme activity, denaturation, and secondary and tertiary structure of the proteins. These investigations on the interaction between glycolipid biosurfactants and model membranes and proteins have been useful and valuable and they advance in the understanding of the molecular mechanism which underlie the varied biological functions exerted by glycolipid biosurfactants.