A thermodynamic appraisal of the radical sink hypothesis.

Analysis of the radical sink hypothesis (C. C. Winterbourn, preceding paper) shows that all reactions are energetically feasible. The process is made irreversible by the formation of superoxide from the GSSG.- anion, which is an extremely favourable reaction, -31 kcal/mol. The overall process has a Gibbs energy change of approximately -50 kcal/mol, depending on the radical that is being "repaired" by glutathione.