Laserspray and Matrix-Assisted Ionization Inlet Coupled to High-Field FT-ICR Mass Spectrometry for Peptide and Protein Analysis

Abstract

We present the first coupling of laser spray ionization inlet (LSII) and matrix assisted ionization inlet (MAII) to high-field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) for generation of electrospray-like ions to take advantage of increased sensitivity, mass range, and mass resolving power afforded by multiple charging. We apply the technique to top-down protein analysis and characterization of metalloproteins. We also present a novel method for generation of multiply-charged copper-peptide complexes with varying degrees of copper adduction by LSII. We show an application of the generated copper-peptide complexes for protein charge state and molecular weight determination, particularly useful for an instrument such as a linear ion trap mass analyzer.

Survival yield comparison between ESI and SAII: Mechanistic implications

“…The internal energy of a peptide has also been shown to be higher using inlet ionization and the matrix 2,5-dihydroxyacetophenone than for ESI, with both methods using the same homebuilt inlet tube at 350 C [32]. In the studies carried out here, the mean SY using 3-NBN was determined to be 26% for p-F and 89% for p-NO 2 ions.…”

Optimization in Detecting Multiply-charged Protein Ions using MALDI TOF-MS

“…A 2-NPG matrix in 50:50 ACN:H 2 O was also used without acid in a recent highvacuum application of LSI. 6 The current analysis demonstrates that the addition of a small amount of TFA (1.0%) to the 2-NPG matrix solution can significantly improve the detection of multiply charged protein ions.…”

Intact protein mass spectrometry and top-down proteomics

“…The native Escherichia coli GroEL complex of 800-kDa displayed ions ranging from 10 to 12,000 m/z and resolution sufficient to count the number of bound ATP molecules was demonstrated. Sarah Trimpin (Wayne State University, MI, USA) described productive work investigating nontraditional ionization methods for intact protein mass spectrometry [5], while Jeff Spraggins (Vanderbilt University, TN, USA) reported on the state-of-the-art intact protein tissue imaging using MALDI Fourier-transform mass spectrometry instrumentation [6].…”