Figure 3. Identification and quantification of Trx1 target SNO-peptides.
A: Example MS/MS spectrum of RL12_HUMAN peptide 17-C*TGGEVGATSALAPK-31 (M2+ 799.44, C*: ICAT-H-labeled cysteine). B: Dramatic increase of SNO-RL12 [Cys17-Lys31] from the MS spectrum of ICAT-L (control) and ICAT-H (SNO-Trx1 treated) ion signals indicates the degree of transnitrosylation. C: Dramatic decrease of SNO-RL12 [Cys17-Lys31] from MS spectrum of ICAT-H (control) and ICAT-L (Trx1/TrxR/NADPH treated) ion signals indicates the degree of denitrosylation. D: MS/MS spectrum of SNO-Trx1 peptide 73-C*MPTFQFFK-81 (M2+ 692.85, C*: ICAT-H-labeled cysteine). E: Dramatic decrease of SNO-Trx1 [Cys73-Lys81] from the MS spectrum of ICAT-L (control) and ICAT-H (SNO-Trx1 treated) ion signals indicates the degree of NO transfer from SNO-Trx1 onto the target proteins. F: Dramatic decrease of SNO-Trx1 [Cys73-Lys81] from MS spectrum of ICAT-H (control) and ICAT-L (Trx1/TrxR/NADPH treated) ion signals indicates the degree of denitrosylation of SNO-Trx1 by reacting with Trx1/TrxR/NADPH.