Open AccessDynamics of ions of intact proteins in the Orbitrap mass analyzer
Author(s) -
Alexander Makarov,
Eduard Denisov
Publication year - 2009
Publication title -
journal of the american society for mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.961
H-Index - 127
eISSN - 1879-1123
pISSN - 1044-0305
DOI - 10.1016/j.jasms.2009.03.024
Subject(s) - chemistry , orbitrap , mass spectrometry , spectrum analyzer , ion , analytical chemistry (journal) , chromatography , organic chemistry , electrical engineering , engineering
While allowing analysis of intact proteins without a theoretical upper mass limit, the Orbitrap mass analyzer demonstrates reduced resolving power as ion mass increases even at a constant mass-to-charge ratio. It is shown that this effect comes from the effects of ion scattering on background gas molecules. The main mechanisms causing decay of acquired transient appear to be fragmentation as well as accelerated dephasing of ion packets. Isotopic resolution of proteins including bovine serum albumin (MW 66.4 kDa) and transferrin (MW 78 kDa) has also been demonstrated. As a part of this study, detection of individual multiply-charged ions of myoglobin (MW 16.9 kDa) has been demonstrated. Quantized distribution of signal intensities for +20 myoglobin ions well above the noise threshold was observed, with high mass accuracy and resolution of recorded individual ions used as an independent confirmation of correct assignment of signal to ions rather than to noise. The latter also allowed us to benchmark the sensitivity of image-current detection and explore in detail factors responsible for signal decay.