|Name||Mrs. Yarixa Cintron-Diaz|
|Organization or Institution||Florida International University|
Protein screening of native brain sections using LESA-TIMS-MS
Yarixa L. Cintron-Diaz, Mario E. Gomez Hernandez, Jennifer Dziedzic, Tomas Guilarte, and Francisco Fernandez-Lima
Florida International University
There is a need for fast, accurate and cost-effective protocols capable of assessing protein content from native brain sections. While different mass spectrometry tools have been able to detect intact molecules from surfaces, in the case of proteins, most of the analysis are limited to low molecular weight (MW) species. In the present work, we take advantage of Liquid Extraction Surface Analysis (LESA) in tandem with nanoESI Trapped Ion Mobility Spectroscopy (nESI-TIMS-MS) for the analysis and identification of protein biomarkers from native brain sections. The added peak capacity of TIMS-MS allows for reduced chemical noise and better detection of protein signals without the need for pre-separation. Tissue sections from monkey animal models were utilized in this study. Brains were extracted, flash frozen and sliced into 12-20 μm sections. LESA extractions were performed using a TriVersa Nanomate device and protein extraction was performed using acetonitrile, water and formic Acid (60:39:1). Samples were characterized offline using a custom built nESI-TIMS coupled to a Bruker Impact q-TOF MS (nESI-TIMS-TOF MS) and a Solarix 7T FT-ICR MS instrument (nESI-FT-ICR MS). Common trends were observed between the LESA protein analysis using nESI-TIMS-TOF MS and nESI-FT-ICR MS. Under these extraction solvent conditions, most proteins appeared denatured, with charge states ranging from +4 to +29 over a 200-1500 m/z. MS profiles are characterized by abundant charge state distributions of highly charged molecules, and most proteins are observed over a narrow charge state range (CSD of 3-4) and cover a MW between 3-21 kDa. Closer inspection of the TIMS-TOF and the FT-ICR MS profile showed eleven common protein signals, while 4 and 12 were unique to TIMS-TOF and FT-ICR MS, respectively. In addition, analysis of brain samples from animals with induced inflammation, resulted in unique protein profiles, with 4/23 proteins being uniquely expressed in the treated animals. Also, the measurement of the collision cross section (CCS) distribution can provide additional information during protein assignment. Different from top-down MS, protein profiling of native brain sections using LESA-TIMS-TOF-MS and LESA-FT-ICR-MS is very sensitive and fast.