Comparative studies of 193-nm photodissociation and TOF-TOFMS analysis of bradykinin analogues: the effects of charge site(s) and fragmentation timescales

J Am Soc Mass Spectrom. 2006 May;17(5):721-9. doi: 10.1016/j.jasms.2006.02.004. Epub 2006 Mar 15.

Abstract

The dissociation reactions of [M + H]+, [M + Na]+, and [M + Cu]+ ions of bradykinin (amino acid sequence RPPGFSPFR) and three bradykinin analogues (RPPGF, RPPGFSPF, PPGFSPFR) are examined by using 193-nm photodissociation and post-source decay (PSD) TOF-TOF-MS techniques. The photodissociation apparatus is equipped with a biased activation cell, which allows us to detect fragment ions that are formed by dissociation of short-lived (<1 mus) photo-excited ions. In our previously reported photodissociation studies, the fragment ions were formed from ions dissociating with lifetimes that exceeded 10 mus; thus these earlier photofragment ion spectra and post-source decay (PSD) spectra [composite of both metastable ion (MI) and collision-induced dissociation (CID)] were quite similar. On the other hand, short-lived photo-excited ions dissociate by simple bond cleavage reactions and other high-energy dissociation channels. We also show that product ion types and abundances vary with the location of the charge on the peptide ion. For example, H+ and Na+ cations can bind to multiple polar functional groups (basic amino acid side chains) of the peptide, whereas Cu+ ions preferentially bind to the guanidino group of the arginine side-chain and the N-terminal amine group. Furthermore, when Cu+ is the charge carrier, the abundances of non-sequence informative ions, especially loss of small neutral molecules (H2O and NH3) is decreased for both photofragment ion and PSD spectra relative to that observed for [M + H]+ and [M + Na]+ peptide ions.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Bradykinin / analogs & derivatives
  • Bradykinin / chemistry*
  • Molecular Sequence Data
  • Peptide Mapping
  • Photochemistry
  • Spectrometry, Mass, Electrospray Ionization / methods*
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / instrumentation
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*
  • Tandem Mass Spectrometry / instrumentation
  • Tandem Mass Spectrometry / methods

Substances

  • Bradykinin