title: Matrix-assisted ionization vacuum for protein detection, fragmentation and PTM analysis on a high resolution linear ion trap-orbitrap platform.
abstract: Matrix-assisted ionization vacuum (MAIV) is a novel ionization technique that generates multiply charged ions in vacuum without the use of laser ablation or high voltage. MAIV can be achieved in intermediate-vacuum and high-vacuum matrix-assisted laser desorption/ionization (MALDI) sources and electrospray ionization (ESI) sources without instrument modification. Herein, we adapt MAIV onto the MALDI-LTQ-Orbitrap XL platform for biomolecule analysis. As an attractive alternative to MALDI for in solution and in situ analysis of biomolecules, MAIV coupling to high resolution and accurate mass (HRAM) MS instrument has successfully expanded the mass detection range and improved the fragmentation efficiency due to the generation of multiply charged ions. Additionally, the softness of MAIV enables potential application in labile post-translational modification (PTM) analysis. In this study, proteins as large as 18.7 kDa were detected with up to 18 charges; intact peptides with labile PTM were well preserved during the ionization process and characterized MS/MS; peptides and proteins in complex tissue samples were detected and identified both in liquid extracts and in situ. Moreover, we demonstrated that this method facilitates MS/MS analysis with improved fragmentation efficiency compared to MALDI-MS/MS.
authors.affiliation: School of Pharmacy, University of Wisconsin-Madison, Madison, WI, 53705, United States.
authors.forename: Bingming
authors.initials: B
authors.lastname: Chen
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53705, United States.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Lietz
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53705, United States.
authors.forename: Chuanzi
authors.initials: C
authors.lastname: OuYang
authors.affiliation: School of Pharmacy, University of Wisconsin-Madison, Madison, WI, 53705, United States.
authors.forename: Xuefei
authors.initials: X
authors.lastname: Zhong
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53705, United States.
authors.forename: Meng
authors.initials: M
authors.lastname: Xu
authors.affiliation: School of Pharmacy, University of Wisconsin-Madison, Madison, WI, 53705, United States; Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53705, United States. Electronic address: lingjun.li@wisc.edu.
authors.forename: Lingjun
authors.initials: L
authors.lastname: Li
mesh_terms: D000818:Animals; D057230:Limit of Detection; D011506:Proteins / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D011506:Proteins
keywords: High resolution and accurate mass; Mass spectrometry; Matrix-assisted ionization vacuum; Multiply charged ions; Post-translational modification; Protein analysis