Determination of structure and properties of modified chlorophylls by using fast atom bombardment combined with tandem mass spectrometry

Richard P. Grese, Ronald L. Cerny, Michael L. Gross, Mathias Senge

Research output: Contribution to journalArticle

51 Scopus citations

Abstract

Tandem mass spectrometry (MS/MS) was used to investigate and compare the decompositions of radical cations (M+.), radical anions (M-.), [M + H]+ ions, and [M + Cat]+ ions (Cat = alkali metal ions) of chlorophylls. Included in this study are chlorophyll a, chlorophyll b, bacteriochlorophyll a, chlorophyll a allomers, and the corresponding pheophytins. Fast atom bombardment of chlorophyll a produces abundant M+. ions, which decompose metastably and upon collisional activation to give fragment ions from losses of the phytyl chain and the β-keto group of ring V. In addition, previously unreported charge-remote fragmentations are useful for identification of branch points on the phytyl chain. Collisional activation of [M + Cat]+ ions produces fragment ions that are complementary to those of the M+ and are used to examine the intrinsic gas-phase reactivity of metal ions and chlorophylls. Peripheral metal ion attachment in chlorophyll a in the gas phase is suggested to be at C-9, and the β-keto ester group at C-10, of ring V. Examination of decompositions of chlorophyll dimers suggests that in the gas phase the interaction between monomers involves bonding of the Mg atom of one chlorophyll a molecule and the C-9 carbonyl oxygen of the other, which was also suggested for chlorophyll a dimers in solution.

Original languageEnglish (US)
Pages (from-to)72-84
Number of pages13
JournalJournal of the American Society for Mass Spectrometry
Volume1
Issue number1
DOIs
StatePublished - Feb 1990

ASJC Scopus subject areas

  • Structural Biology
  • Spectroscopy

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