Electrospray Photochemical Oxidation of Proteins

R.O. Lawal, F. Donnarumma, K.K. Murray, Electrospray Photochemical Oxidation of Proteins, J. Am Soc. Mass Spectrom. doi:10.1007/s13361-019-02313-4

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Abstract

Electrospray Photochemical Oxidation of Proteins
Electrospray Photochemical Oxidation of Proteins

Photooxidation of peptides and proteins by pulsed ultraviolet laser irradiation of an electrospray in the ion source of a mass spectrometer was demonstrated. A 193-nm excimer laser at 1.5-mJ pulse energy was focused with a cylindrical lens at the exit of a nanoelectrospray capillary and ions were sampled into a quadrupole time-of-flight mass spectrometer. A solution containing a peptide or protein and hydrogen peroxide was infused into the spray at a flow rate of 1 μL/min using a syringe pump. The laser creates OH radicals directly in the spray which modify biomolecules within the spray droplet. These results indicate that photochemical oxidation of proteins can be initiated directly within electrospray droplets and detected by mass spectrometry.

A Nanoparticle Co-matrix for Multiple Charging in MALDI Imaging of Tissue

B. Banstola, K.K. Murray, “A Nanoparticle Co-matrix for Multiple Charging in MALDI Imaging of Tissue,” Rapid Commun. Mass Spectrom. 16 (2019) 12. doi:10.1002/rcm.8424.

Abstract
Rationale: A two‐component matrix of 2‐nitrophloroglucinol (2‐NPG) and silica nanoparticles was used for matrix‐assisted laser desorption ionization (MALDI) mass spectrometry imaging of high‐charge‐state biomolecules in tissue. Potential advantages include increased effective mass range and efficiency of fragmentation.
Methods: A mixture of 2‐NPG matrix and silica nanoparticles was applied to cyrosectioned 10 μm thick mouse brain tissue. The mixture was pipetted onto the tissue for profiling and sprayed for tissue imaging. MALDI images were obtained under high vacuum in a commercial time‐of‐flight mass spectrometer.
Results: The combined 2‐NPG and nanoparticle matrix produced highly charged ions from tissue with high‐vacuum MALDI. Nanoparticles of 20, 70, 400, and 1000 nm in diameter were tested, the 20 nm particles producing the highest charge states. Images of mouse brain tissue obtained from highly charged ions show similar spatial localization.
Conclusions: The combined 2‐NPG and nanoparticle matrix produces highly charged ions from tissue through a mechanism that may rely on the high surface area of the particles which can dry the tissue, and their ability to bind analyte molecules thereby assisting in crystal formation and production of multiply charged ions on laser irradiation.

Nanoparticle Co-matrix Figure 4
Images of consecutive mouse brain tissue sections obtained from 8565 m/z and its multiply charged ions with a) 2-NPG, and b) 2-NPG/nanoparticle matrix.

Matrix-Assisted Laser Desorption Ionization Imaging and Laser Ablation Sampling for Analysis of Fungicide Distribution in Apples

I. Pereira, B. Banstola, K. Wang, F. Donnarumma, B.G. Vaz, K.K. Murray, Matrix-Assisted Laser Desorption Ionization Imaging and Laser Ablation Sampling for Analysis of Fungicide Distribution in Apples, Anal. Chem. 91 (2019) 6051–6056. doi:10.1021/acs.analchem.9b00566.

ABSTRACT: A combination of matrix-assisted laser desorption ionization (MALDI) imaging and infrared (IR) laser ablation sampling with offline electrospray ionization mass spectrometry (ESI-MS) was used to determine the distribution of the fungicide imazalil in apples. MALDI images were used to determine the penetration depth of imazalil up to 7 days after its application. IR laser ablation sampling and ESI-MS were used to quantify the rate of penetration of the fungicide, which was determined to be approximately 1 mm per day. Imazalil concentration decreased in the apple skin over the course of the experiment, and after 7 days the fungicide was detected at 0.015 ppm 6 mm inside the apple. Approximately 60% of the pesticide remained in the skin after 7 days. This work demonstrates the utility of MALDI imaging for spatial localization of fungicide in fruit in combination with IR laser ablation and ESI-MS for quantitative analysis.

Matrix-Assisted Laser Desorption Ionization Imaging and Laser Ablation Sampling for Analysis of Fungicide Distribution in Apples
Pereira, Banstola, Wang, Donnarumma, Vaz, Murray, Matrix-Assisted Laser Desorption Ionization Imaging and Laser Ablation Sampling for Analysis of Fungicide Distribution in Apples, Anal. Chem. 91 (2019) 6051

Piezoelectric matrix-assisted ionization

B. Banstola, C.W. Szot, A.P. Deenamulla Kankanamalage, K.K. Murray, Piezoelectric matrix-assisted ionization, Eur J Mass Spectrom 25 (2019) 202–207. doi:10.1177/1469066718816696

ABSTRACT: We have developed a new actuation method for matrix-assisted ionization with good temporal and spatial resolution using piezoelectric cantilever. A strike from the piezoelectric bimorph cantilever on a thin metal foil was used to remove materials deposited on the opposite side facing the mass spectrometer inlet. Highly charged ions of peptides and proteins were generated from dried droplet deposits and sampled into the inlet of the mass spectrometer. A lateral resolution of 1 mm was obtained with the piezoelectric sampling configuration. Singly charged lipids and gangliosides were detected from tissue with piezoelectric matrix-assisted ionization using a silica nanoparticle co-matrix.

Piezoelectric MAI at inlet to the Bruker Amazon ion trap

ASMS 2019: Deep-ultraviolet Laser Ablation Sampling for Mass Spectrometry

MOG 03:10pm
Deep-ultraviolet Laser Ablation Sampling for Mass Spectrometry
Remilekun O. Lawal; Fabrizio Donnarumma; Kermit K. Murray

193 nm excimer laser ablation setup
193 nm excimer laser ablation setup

High resolution sampling of biological systems is crucial to revealing the differences in proteins and metabolites amongst heterogeneous cells. Laser ablation sampling for mass spectrometry is a powerful method for analyzing biomolecules in tissue under ambient conditions with high spatial control while eliminating the need for external matrices. It allows off-line analysis by liquid chromatography tandem mass spectrometry and can be combined with mass spectrometry imaging for region of interest selection. The most efficient lasers currently used for ablation sampling use mid-infrared wavelengths that are diffraction limited to spot sizes tens of micrometers in diameter. Short wavelength lasers can be focused to order of magnitude smaller spot sizes for efficient ablation with minimal thermal damage to adjacent sample areas.

ASMS 2019: Charge Production by Sublimation of Organic Compounds in Matrix Assisted Ionization

WOG 03:30pm
Charge Production by Sublimation of Organic Compounds in Matrix Assisted Ionization
Bijay Banstola; Kermit K. Murray

Dual vacuum chamber used to measure sublimation electrification

Matrix assisted ionization (MAI) describes a mode of ionization in which an analyte molecule is mixed with an organic matrix and produces ions when the dried matrix and analyte containing crystals are exposed to external shock or sublime under vacuum. MAI produces highly charged ions from large biopolymers with charge distributions similar to electrospray ionization. When exposed to vacuum, the matrix crystals fracture, which may eject charged particles and clusters containing matrix and analyte or may directly eject highly charged ions. In this study, a method was developed to measure the charge produced during the sublimation of MAI matrix compounds. Sublimation charge production was measured as a function of matrix, crystal size and morphology, pH, and temperature.

ASMS 2019

Murray Group Presentations

Orals

MOG 03:10pm

Deep-ultraviolet Laser Ablation Sampling for Mass Spectrometry
Remilekun O. Lawal; Fabrizio Donnarumma; Kermit K. Murray

WOG 03:30pm


Charge Production by Sublimation of Organic Compounds in Matrix Assisted Ionization
Bijay Banstola; Kermit K. Murray

Posters

MP 765

Cellular Precision for Infrared Laser Ablation Tissue Microproteomics
Chao Dong; Fabrizio Donnarumma; Kelin Wang; Kermit K. Murray

TP 266


Forensic Sampling Using Nanoparticle Extraction and Capture
Jamira A Stephenson; Fabrizio Donnaruma; Kermit K Murray

TP 362


Optimizing Tissue Ablation for Mass Spectrometry Imaging Using Light Scattering
Achala P Deenamulla Kankanamalage; Fabrizio Donnaruma; Kermit K Murray

WP 433


Software for Automated Laser Ablation and Capture from Tissue Sections
Fabrizio Donnarumma; Touradj Solouki; Kermit K Murray

WP 518
Simultaneous Extraction of Proteins, Lipids, and Metabolites for Integrated-omics Approaches for Low Tissue Sampling Volumes
Luke T. Richardson; Amy N. W. Schnelle; Fabrizio Donnaruma; Michael E. Pettit;

ThP 050


Two-Laser Ablation Electrospray Ionization Mass Spectrometry
Kelcey B. Hines; Remilekun O. Lawal; Fabrizio Donnarumma; Kermit K. Murray

ThP 124
Influence of Traumatic Brain Injury on Bile Acid Profiles in the Brains of Rats
Amy N. W. Schnelle; Luke T. Richardson; Fabrizio Donnaruma; Ashok K. Shetty; Kermit K Murray; Touradj Solouki

ThP 413


MALDI-directed Region Selection for Laser Ablation Tissue Microsampling
Kelin Wang; Fabrizio Donnarumma; Michael Pettit; Touradj Solouki; Kermit K. Murray

Deep‐ultraviolet laser ablation electrospray ionization mass spectrometry

R.O. Lawal, F. Donnarumma, K.K. Murray, Deep-ultraviolet laser ablation electrospray ionization mass spectrometry, J. Mass Spectrom.54 (2019) 281–287. doi:10.1002/jms.4338.

Abstract
Myoglobin ionized by (a) 193 nm laser ablation electrospray and (b) electrospray
Myoglobin ionized by (a) 193 nm laser ablation electrospray and (b) electrospray

A 193‐nm wavelength deep ultraviolet laser was used for ambient laser ablation electrospray ionization mass spectrometry of biological samples. A pulsed ArF excimer laser was used to ablate solid samples, and the resulting plume of the desorbed material merged with charged electrospray droplets to form ions that were detected with a quadrupole time‐of‐flight mass spectrometer. Solutions containing peptide and protein standards up to 66‐kDa molecular weight were deposited on a metal target, dried, and analyzed. No fragmentation was observed from peptides and proteins as well as from the more easily fragmented vitamin B12 molecule. The mass spectra contained peaks from multiply charged ions that were identical to conventional electrospray. Deep UV laser ablation of tissue allowed detection of lipids from untreated tissue. The mechanism of ionization is postulated to involve absorption of laser energy by a fraction of the analyte molecules that act as a sacrificial matrix or by residual water in the sample.