Heuristic charge assignment for deconvolution of electrospray ionization mass spectra.
We propose a new algorithm for deconvolution of electrospray ionization mass spectra based on direct assignment of charge to the measured signal at each mass-to-charge ratio (m/z). We investigate two heuristics for charge assignment: the entropy-based heuristic is adapted from a deconvolution algorithm by Reinhold and Reinhold;10 the multiplicative-correlation heuristic is adapted from the multiplicative-correlation deconvolution algorithm of Hagen and Monnig.6 The entropy-based heuristic is insensitive to overestimates of z(max), the maximum ion charge. We test the deconvolution algorithm on two single-component samples: the measured spectrum of human beta-endorphin has two prominent and one very weak line whereas myoglobin has a well-developed quasi-gaussian envelope of 17 peaks. In both cases, the deconvolution algorithm gives a clean deconvoluted spectrum with one dominant peak and very few artefacts. The relative heights of the peaks due to the parent molecules in the deconvoluted spectrum of a mixture of two peptides, which are expected to ionize with equal efficiency, give an accurate measure of their relative concentration in the sample.
Zheng
Huiru
H
Faculty of Informatics, University of Ulster at Jordanstown, Newtownabbey BT37 0QB, Northern Ireland.
Ojha
Piyush C
PC
McClean
Stephen
S
Black
Norman D
ND
Hughes
John G
JG
Shaw
Chris
C
D000465:Algorithms; D000818:Animals; D001920:Bradykinin / Q000032:analysis; D025802:Electric Capacitance; D004553:Electric Conductivity; D019277:Entropy; D006801:Humans; D007477:Ions; D009211:Myoglobin / Q000032:analysis; D010455:Peptides / Q000737:chemistry; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000706:statistics & numerical data*; D001615:beta-Endorphin / Q000032:analysis
D007477:Ions; D009211:Myoglobin; D010455:Peptides; D001615:beta-Endorphin; D001920:Bradykinin