Journalartikel

Jahr der Veröffentlichung: 2006

Seiten: 2404-2410

Zeitschrift: Rapid Communications in Mass Spectrometry

Bandnummer: 20

Heftnummer: 16

ISSN: 0951-4198

DOI Link: https://doi.org/10.1002/rcm.2598

Verlag: Wiley

Abstract: 
In an analysis of a combined chymotrypsin/AspN digest of galectin-3 by positive ion nano-electrospray ionisation mass spectrometry (nanoESI-MS) several peptides were observed which showed metal adduct ions as their most abundant ion signals. The most prominent adduct ions were observed at m/z values corresponding to [M+40](2+), [M+41](3+), and [M+42](4+) ions. Detailed investigation of the [M+40](2+) ion of the peptide GAPAGPLIVPY showed that it was not, as originally expected, a [M+H+K-39](2+) adduct ion but had the.composition [M+Ca-40](2+). This was verified by several approaches: W nanoESI-MS/MS of the [M+Ca](2+) adduct ions resulted in the virtually exclusive formation of doubly charged fragment ions; (ii) mass determination by quadrupole time-of-flight (QTOF)-MS provided a preliminary identification; and (iii) accurate mass measurement using nanoESI Fourier transform ion cyclotron resonance (FTICR)-MS at a mass resolving power of 500000 allowed the specific detection and identification of the isobaric ion pairs [M+Ca-40](2+)/ [M+H+K-39](2+) and [M+Mg-24](2+)/[M+H+(23) Na](2+). All peptides in the chymotryptic galectin-3 digest without a basic residue (K or R) showed addition of calcium as the most prominent ionisation principle. A further common feature of these nonbasic peptides was the presence of several proline residues, which is assumed to be a factor promoting the intense addition of calcium. It was observed that the common trace levels of sodium and calcium in analytical grade solvents (about 1-10 mu M) are sufficient to generate the [M+H+Na-23](2+) and [M+Ca-40](2+) ions as the most prominent species of the peptide GAPAGPLIVPY. We conclude that the sequence motifs P-XX-P and P-XXX-P favour the solvation of alkaline earth ions in ESI-MS. In view of the successful detection of physiological Ca/ protein interactions by ESI-MS, this finding may point to a solvation of Ca2+ by galectin in solution. The findings open new routes of research in the study of metal/protein and metal/peptide interactions.

Harvard-Zitierstil: Lehmann, W., Wei, J., Hung, C., Gabius, H., Kirsch, D., Spengler, B., et al. (2006) Effective solvation of alkaline earth ions by proline-rich proteolytic peptides of galectin-3 upon electrospray ionisation, Rapid Communications in Mass Spectrometry, 20(16), pp. 2404-2410. https://doi.org/10.1002/rcm.2598

APA-Zitierstil: Lehmann, W., Wei, J., Hung, C., Gabius, H., Kirsch, D., Spengler, B., & Kübler, D. (2006). Effective solvation of alkaline earth ions by proline-rich proteolytic peptides of galectin-3 upon electrospray ionisation. Rapid Communications in Mass Spectrometry. 20(16), 2404-2410. https://doi.org/10.1002/rcm.2598