Biological redox processes, pulse

Radiation chemistry, and pulse radiolysis in particular, is now a mature subject that is available as a very valuable and a powerful tool by which fundamental problems in free radical reaction mechanisms can be addressed. This chapter is restricted to studies concerning sulfur-centered radicals and radical-ions performed by radiation chemistry techniques in the first eight years of XXI century (2001-2008). SuMur-centered radicals represent a very interesting class of radicals since they exhibit very interesting redox chemistry, including biological redox processes, and different spectral and kinetic properties as... 

The potential of pulse radiolysis for studying biological redox processes, particularly of macromolecules, was recognized rather early. It was initially employed for investigating radiation-induced damage and, later on, as an effective tool for resolving electron transfer processes to and within proteins. Cytochrome c, a well-characterized electron-mediating protein, was the first to be... 

Pecht, I., Goldberg, M. Electron transfer pathways to and within redox proteins Pulse radiolysis studies. In Fast Processes in Radiation Chemistry and Biology (Adams, G. E., Fielden, E. M., Michael, B. D., eds.), Wiley, Chichester-New York-Toronto-Sydney, 1975, pp. 277-284... 

Pulse radiolysis has been employed successfully to resolve mechanisms of action of redox proteins and of electron transfer within their polypeptide matrix. The limitations on the use of this method, set by the requirement for expensive electron accelerators, are more than compensated for by experimental advantages, as illustrated by the results described in this chapter. Future applications to the study of engineered proteins and other model systems would certainly extend our understanding of both of these aspects of redox processes in biological macromolecules. 

The many methods to initiate lipid peroxidation in vitro, such as azo initiators, metal ions, pulse radiolysis, photoinitiation (Type I), enzymes (oxidases), to mention a few, have been reviewed . However, as Bucala emphasized in a review ", oxidation initiation is a pivotal first step and there is little understanding of how initiation proceeds in vivo. Transition metal ions, iron or copper, are frequently used to initiate lipid oxidation, but free (unchelated) redox-active transition metals are virtually absent from biological systems" and appear to have little bearing on known pathological processes ". 

---