Effects of oxidative damage of membrane protein thiol groups on erythrocyte membrane viscoelasticities

In three oxidative damaging systems: the diamide-mercaptoethanol redox modi fication system (DM), the pyrogallol oxygen free radicals system (PG) and t he hypoxanthine-xanthine oxidase oxygen free radical system (HXO), the effe ct of erythrocyte membrane oxidative damage on membrane viscoelasticities w as investigated with micropipette aspiration method. The experimental resul ts indicated that erythrocyte membrane oxidative damage has a great influen ce upon the membrane mechanical properties. The oxidative damage led to dec rease of contents of membrane protein thiol radical. The scanning of SDS-PA GE presented that membrane proteins form the higher molecular weight compon ent (HMP) by the cross-linking of membrane protein thiol radicals that migh t hinder the conformational change of membrane protein. This might be the r eason for the increased membrane elastic modulus and viscous coefficient up on treating erythrocytes with the oxidative damaging systems. A significant negative logarithm regression relation was found between the membrane elas tic modulus, mu, or viscoefficient, eta, and the contents of membrane prote in thiol radicals. These experimental results suggested that thiol radicals oxidative damage reaction due to the superoxides anions (O-.(2)-) may be a n important molecular mechanism inducing changes of membrane viscoelasticit ies or whole cell deformability of erythrocyte under physiological and path ological oxidative stress.