Rhodopsin kinase: Two mAbs binding near the carboxyl terminus cause time-dependent

Two mAbs generated against rhodopsin kinase (RK) were charac-terized for their epitopes. Both antibodies recognize short peptidesequences,overlappingbutdistinct,closetothecarboxylterminus.BindingofRKtotheantibodiesisslow.Attemptsweremadetousethe antibodies immobilized on protein A-Sepharose beads to bindand purify the enzyme. Time-dependent inactivation of the en-zyme occurred after its binding to the antibodies. Studies usingdifferent conditions to maintain the enzyme in the active formduring binding or to reactivate the purified inactivated enzymewere unsuccessful.