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. Author manuscript; available in PMC: 2017 Sep 2.
Published in final edited form as: J Proteome Res. 2016 Aug 18;15(9):3139–3146. doi: 10.1021/acs.jproteome.6b00266

Figure 1.

Figure 1

Oxidation of doubly protonated S-ethyl RAKGCKGR upon ion/ion reaction with IO4−. (a) Ion/ion reaction between RAKGC(Et)KGR [M + 2H]2+ and IO4−. Activation of the (b) ion/ion complex, (c) [M + H + O]+ species, and (d) HOSEt loss. Insets show structures of (a) S-ethyl cysteine, (b, c) oxidized S-ethyl cysteine, and (d) dehydroalanine product formed upon loss of HOSEt. Symbols are as follows: (red squares) loss of HOSR to form the dehydroalanine product, (○) water losses, (*) ammonia losses, (lightning bolts) species subjected to CID, and (□) fragment ions that have lost the HOSR group.