Fig. 2. Stability of (A) GP1 and (B) GP2 in PBS, MEM, RPMI-1640, pH 5 H2O, and porcine liver esterase (PLE) in PBS. The observed partial reduction over long periods of time in RPMI-1640 is likely a result of glutathione (GSH) in the media. Both agents are highly stable in PBS, MEM, and pH 5 H2O over extended periods of time while PLE resulted in slight decrease in stability. Stability of (C) GP1 and (D) GP2 in 5 mM GSH and 5 mM ascorbate. GP1 and GP2 are both rapidly reduced by intracellular concentrations of GSH.
