SCHISTOSOMA-MANSONI - SURFACE-MEMBRANE ISOLATION WITH LECTIN-COATED BEADS

Lectins from Lens culinaris and Arachis hypogaea immobilized on polyac rylamide beads were used for selective isolation of glycosylated surfa ce membrane domains of adult Schistosoma mansoni worms, and the method was compared with the membrane isolation procedure developed with pol ycationic (Affi-Gel) beads. The lentil lectin proved to be suitable fo r interaction with surface membrane components: an increment in the sp ecific activities of tegumental phosphohydrolases was observed in the bound fraction with respect to that observed in a total worm homogenat e. A characteristic polypeptide pattern on gel electrophoresis was als o seen, more restricted than that obtained with the bound Affi-Gel fra ction. Immobilized peanut lectin was not successful as a method for is olating membrane material from the tegument of adult worms. Solubiliza tion and dissociation of the lentil lectin-bound enzyme markers was ac hieved after addition of detergent and competing sugars. Glycosylation of the solubilized enzymes was further confirmed by affinity chromato graphy with fresh lentil lectin-coated beads. These results, together with histochemical evidences, suggest that the active sites of some of these enzymes are locted within or close to the cytoplasmic leaflet o f the surface tegumental membranes, and allow us to propose a model fo r the double surface membrane complex where some proteins may be cross ing the two bilayers.