Improved N- and C-terminal sequencing of proteins by combining positive and negative ion MALDI in-source decay mass spectrometry

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Nicolardi, S, Kilgour, DPA ORCID: https://orcid.org/0000-0002-3860-7532, Van Der Burgt, YEM and Wuhrer, M, 2020. Improved N- and C-terminal sequencing of proteins by combining positive and negative ion MALDI in-source decay mass spectrometry. Analytical Chemistry. ISSN 0003-2700

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Official URL: https://doi.org/10.1021/acs.analchem.0c02198

Abstract

The development of various ionization and fragmentation techniques has been of key importance for establishing mass spectrometry (MS) as a powerful tool for protein characterization. One example of this is matrix-assisted laser desorption/ionization (MALDI) combined with in-source decay (ISD) fragmentation that allows mapping of N- and C-terminal regions of large proteins without the need for proteolysis. Positive ion mode ISD fragments are commonly assigned in the mass region above m/z 1000, while MALDI matrix ions generally hamper the detection of smaller singly-charged fragments. The ultrahigh resolving power provided by Fourier transform ion cyclotron resonance (FT-ICR) MS partially overcomes this limitation, but to further increase detection of smaller fragments we have revisited the application of negative ion mode MALDI-ISD and found a good coverage of the peptide chain termini starting from c’2 and z’2 fragment ions. For the first time, we demonstrate that the combination of negative and positive ion MALDI FT-ICR MS is a useful tool to improve the characterization of mAbs. The different specificities of the two ion modes allowed us to selectively cover the sequence of the light and heavy chains of mAbs at increased sensitivity. A comprehensive evaluation of positive and negative ion mode MALDI-ISD FT-ICR MS in the m/z-range 46-13,500 showed an increased sequence coverage for three standard proteins, namely myoglobin, SiLuLite mAb, and NIST mAb. The data obtained in the two ion modes were, in part, complementary.

Item Type:	Journal article
Publication Title:	Analytical Chemistry
Creators:	Nicolardi, S., Kilgour, D.P.A., Van Der Burgt, Y.E.M. and Wuhrer, M.
Publisher:	American Chemical Society (ACS)
Date:	17 August 2020
ISSN:	0003-2700
Identifiers:	Number Type 10.1021/acs.analchem.0c02198 DOI 1355243 Other
Divisions:	Schools > School of Science and Technology
Record created by:	Linda Sullivan
Date Added:	24 Aug 2020 15:44
Last Modified:	17 Aug 2021 03:00
URI:	https://irep.ntu.ac.uk/id/eprint/40505