A KINETIC-STUDY OF CONCANAVALIN-A BINDING TO GLYCOLIPID MONOLAYERS BY USING A QUARTZ-CRYSTAL MICROBALANCE

Specific binding and dissociation processes of concanavalin A (Con A) to a mixed monolayer containing synthetic glycolipids at the air-water interface were observed from frequency changes of a quartz-crystal microbalance (QCM) that was attached horizontally on the monolayer from the air phase. Binding constants (k(1)), dissociation rate constants (k(-1)), and binding amount (Delta m) could be obtained from time courses of the frequency decrease (mass increase) of the QCM. Con A showed the specific binding to 2C(18)-mal lipids having a glucopyranosyl head group but not ?Cls-lac lipids having a galactopyranosyl head group in the matrix of phosphoethanolamine lipids (2C(18)PE). The maximum binding amount (Delta m(max)) was independent of the mole fraction of the 2C(18)-mal, but on the contrary, binding (k(1)), dissociation rate (k(-1)), and association constants (K-a = k(1)/k(-1)) were affected largely by the content of the 2C(18)-mal in the monolayer.