SITS Derivatization of Peptides to Enhance 266 nm Ultraviolet Photodissociation (UVPD)by Quick, MM; Mehaffey, MR; Johns, RW; Parker, WR; Brodbelt, JS
N-terminal derivatization of peptides with the chromogenic reagent 4acetamido- 4-isothiocyanatostilbene-2,2-disulfonic acid (SITS) is demonstrated to enhance the efficiency of 266 nm ultraviolet photodissociation (UVPD). Attachment of the chromophore results in a mass shift of 454 Da and provides significant gains in the number and abundances of diagnostic fragment ions upon UVPD. Activation of SITS-tagged peptides with 266 nm UVPD leads to many fragment ions akin to the a/b/y ions commonly produced by CID, along with other sequence ions (c, x, and z) typically accessed through higher energy pathways. Extreme bias towards Cterminal fragment ions is observed upon activation of SITS-tagged peptides using multiple 266 nm laser pulses. Due to the high reaction efficiency of the isothiocyanate coupling to the N-terminus of peptides, we demonstrate the ability to adapt this strategy to a high-throughput LCMS/ MS workflow with 266 nm UVPD.