Organic chemistry

Electrospray

Biomolecule

Operating system

Analytical Chemistry (journal)

Dissociation (chemistry)

Desorption electrospray ionization

Biomedical engineering

Top-down proteomics

Physical chemistry

Ion-mobility spectrometry

Mass spectrometry

Mass spectrometry imaging

Chemistry

Fragmentation (computing)

Ionization

Protein mass spectrometry

Biological tissue

Computer science

Chemical ionization

Electrospray ionization

Chromatography

Biochemistry

Medicine

Analytical Chemistry

Analysis of large biomolecules including proteins has proven challenging using ambient ionization mass spectrometry imaging techniques. Here, we have successfully optimized desorption electrospray ionization mass spectrometry (DESI-MS) to detect intact proteins directly from tissue sections and further integrated DESI-MS to a high field asymmetric waveform ion mobility (FAIMS) device for protein imaging. Optimized DESI-FAIMS-MS parameters were used to image mouse kidney, mouse brain, and human ovarian and breast tissue samples, allowing detection of 11, 16, 14, and 16 proteoforms, respectively. Identification of protein species detected by DESI-MS was performed on-tissue by top-down ultraviolet photodissociation (UVPD) and collision induced dissociation (CID) as well as using tissue extracts by bottom-up CID and top-down UVPD. Our results demonstrate that DESI-MS imaging is suitable for the analysis of the distribution of proteins within biological tissue sections.

Desorption Electrospray Ionization Mass Spectrometry Imaging of Proteins Directly from Biological Tissue Sections