that oxidoreductasemediated modulations of the cell surface thiol status affect the enzymatic activity of APN .
Additional evidence for the pivotal role of extracellular cysteines in the APN molecule was obtained
We show here that oxidoreductasemediated modulations of the cell surface thiol status affect the enzymatic activity of APN .
Additional evidence for the pivotal role of extracellular cysteines in the APN molecule was obtained when substitution of any of these six cysteines caused complete loss of surface expression and enzymatic activity .