20] Pulse radiolysis

Abstract

Publisher Summary The technique of pulse radiolysis, which was originally developed to study fast primary processes in radiation chemistry, is the radiation chemical analog of flash photolysis). In essence, the technique employs an intense pulse of ionizing radiation, usually of submicrosecond duration, to generate a high concentration of reactive intermediates, the chemical reactions of which may be followed by UV-VIS spectrophotometry. Time resolution down to 10 nsec is easily achieved, and in several instances this has been reduced to the picosecond domain. For metalloprotein studies it is, however, also important that processes extending over seconds can be followed. Other modes of detection have been used including conductivity, electron paramagnetic resonance (EPR), and polarography, but kinetic spectrophotometry is by far the most versatile and the most used for studies on proteins, and this chapter confines its consideration to this method. The value of the pulse radiolysis technique to studies on proteins and enzyme systems stems from the fact that the radiolysis of water and aqueous solutions provides a means of generating, in a controlled way, a wide range of one-electron oxidizing and reducing agents, which may be used to characterize and study protein function.