Detection of Ras GTPase protein radicals through immuno-spin trapping

► Evidence of
- NO-mediated protein radical formation in HRas is presented. ► Immuno-spin trapping (IST) and tandem mass spectrometry indicate a Cys118 Ras protein radical. ► IST may be used to detect thiyl radical formation in the Ras oncoprotein. ► The IST approach described can be used for other nonmetalloproteins.