Ultraviolet Photodissociation of Carboxylate-Derivatized Peptides in a Quadrupole Ion Trap |
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Authors: | Byoung Joon Ko Jennifer S Brodbelt |
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Institution: | (1) Department of Chemical Engineering, University of Texas at Austin, 1 University Station A5300, Austin, TX, USA;(2) Department of Chemistry & Biochemistry, The University of Texas at Austin, 1 University Station A5300, Austin, TX 78712, USA; |
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Abstract: | The fragmentation patterns obtained by ultraviolet photodissociation (UVPD) and collision-induced dissociation (CID) in a
quadrupole ion trap mass spectrometer were compared for peptides modified at their C-termini and at acidic amino acids. Attachment
of Alexa Fluor 350 or 7-amino-4-methyl-coumarin chromophores at the C-terminal and acidic residues enhances the UV absorptivity
of the peptides and all fragment ions that retain the chromophore, such as the y ions that contain the chromophore-modified
C-terminus. Whereas CID results in the formation of the typical array of mainly y-type and a/b-type fragment ions, UVPD produces
predominantly a/b-type ions with greatly reduced abundances of y ions. Immonium ions, mostly ones from aromatic or basic amino
acids, are also observed in the low m/z range upon UVPD. UVPD of peptides containing two chromophore moieties (with one at the C-terminus and another at an acidic
residue) results in even more efficient photodissociation at the expense of the annihilation of almost all diagnostic b and
y ions containing the chromophore. |
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Keywords: | |
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