Contrasting oxygen-effects in the inactivation of ribonuclease A by N.3, (SCN).-2 and .OH radicals.
N.3 exhibits higher efficiency than .OH in the inactivation of RNase in de-acerated (neutral) aqueous solution. In O2-saturated solution the .OH-induced inactivation is enhanced, but N.3 and (SCN).-2 become remarkably inefficient. Our results suggest that semi-oxidized tyrosine, the predominant initial defect induced by N.3 and (SCN).-2 but not by  .OH2 can be re-reduced upon reaction with O.-2 or cysteine.
D055598:Chemical Phenomena; D002621:Chemistry; D003037:Cobalt Radioisotopes; D004307:Dose-Response Relationship, Radiation; D005609:Free Radicals; D005720:Gamma Rays; D006878:Hydroxides; D009584:Nitrogen; D010100:Oxygen; D012260:Ribonucleases / Q000528:radiation effects*; D013861:Thiocyanates
D003037:Cobalt Radioisotopes; D005609:Free Radicals; D006878:Hydroxides; D013861:Thiocyanates; D012260:Ribonucleases; D009584:Nitrogen; D010100:Oxygen