Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2003 Oct;38(10):1105-9.
doi: 10.1002/jms.530.

Fragmentation of tunichrome Sp-1 is dominated by an unusual gas-phase intramolecular rearrangement

Affiliations

Fragmentation of tunichrome Sp-1 is dominated by an unusual gas-phase intramolecular rearrangement

Steven W Taylor et al. J Mass Spectrom. 2003 Oct.

Abstract

Tunichrome Sp-1 is a modified pentapeptide from the ascidian Styela plicata, having the structure H-DOPA-DOPA-Gly-Pro-dcDeltaDOPA (where DOPA = 3,4-dihydroxyphenylalanine and dcDeltaDOPA = decarboxy-(E)-alpha,beta-dehydro-DOPA). The tandem mass spectrum of the peptide is dominated by a number of abundant fragment ions that involve a gas-phase rearrangement where the dcDeltaDOPA group becomes covalently attached to the N-terminus. The high degree of rearrangement in Sp-1 compared with a related octapeptide, plicatamide, allowed for detailed multiple mass spectrometric (MS(n)) (up to n = 6) experiments, and hence permitted a detailed assessment of the origin and routes to the formation of the various rearrangement ions. Analyses on both a triple-quadrupole and a quadrupole time-of-flight mass spectrometer were made to ascertain whether the gas-phase rearrangements observed for tunichrome Sp-1 were unique to an ion trap mass spectrometer (i.e. the hypothesis being that perhaps the extended trapping times were required to facilitate this unusual gas-phase rearrangement). Interestingly, analyses on both the triple-quadrupole and quadruple time-of-flight mass spectrometers revealed an identical phenomenon, with the rearrangement fragment ions present at approximately the same abundance as the non-rearranged a-, b- and y-type sequence ions. We suggest that the smaller size of tunichrome Sp-1 compared with plicatamide facilitates the transfer of the dcDeltaDOPA group in this gas-phase rearrangement. This rearrangement was not observed for peptide analogs of tunichrome Sp-1 that did not contain the dcDeltaDOPA at the C-terminus, confirming that the presence of dcDeltaDOPA is critical for the rearrangement.

PubMed Disclaimer

Publication types

LinkOut - more resources