The radiolysis of aqueous solutions containing dithiothreitol and oxidized dithiothreitol

Abstract

The radiation chemistry of aqueous solutions (pH 1-9) of dithiothreitol (DTT) has been investigated by pulsed and steady-state techniques. From G( H 2 S) in N 2- and N 2O-saturated solutions it was concluded for pH 5–9 that the majority of the solvated electrons and 25–40% of the hydroxyl radicals reacted with DTT to form H 2S. Oxidized dithiothreitol (DTT- ox) was the other major product observed for pH 5–9. However, DTT- ox was not formed when DTT solutions were irradiated at pH 1 and 2. When nitrate ions were added as an electron scavenger over the pH range 5–9, G( DTT- ox) was not affected; at pH 9.0 G( H 2 S) decreased slightly but at pH 5–6, G( H 2 S) was reduced to that arising from the reaction of the hydroxyl radical. The reaction of CO 2 - with DTT- ox was studied at pH 4.6 and pH 9.0. At pH 9.0 the G( DTT)=3.3−0.2 indicated a simple two electron reduction of DTT- ox while at pH 4.6 the G( DTT) >25 implied a chain reaction had occurred.