Biology Reference
In-Depth Information
Chapter 17
Mass Spectrometry-Based Imaging of Metabolites
and Proteins
Manuela Peukert , Michael Becker , Andrea Matros , and Hans-Peter Mock
Abstract
Imaging techniques based on mass spectrometry (MS) have become powerful approaches to decipher the
spatial distribution of metabolites and proteins. MS imaging (MSI) mostly relies on matrix-assisted laser
desorption/ionization coupled to MS detection, but desorption electrospray ionization is also frequently
used. Here we describe our current protocols for MALDI-MSI of seed sections and for root tissue.
Detailed procedures for cryo-sectioning, matrix application, image capture, mass spectrometry measure-
ment and data analysis are given.
Key words
Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI),
Barley grains, Tobacco roots, Small molecules, Proteins
1
Introduction
MS-based imaging of tissues has found widespread applications in
medicinal and pharmaceutical studies [
1
-
4
]. The approach pro-
vides information about the spatial distributions of small molecules
and proteins within tissues. It has been used to study molecular
features associated with lung tumors [
5
], gliomas [
6
] or with breast
cancer [
7
] and the distribution of drug candidates [
8
].
The prevalent technique in MS-based imaging involves the
use of a MALDI source. Tissue sectioning and the application of
a suitable matrix are fundamental steps prior to the sampling of
MS data. Both processes are essential to obtain images with high
resolution. Tissue sectioning has to be adapted for specifi c tissues.
The selection of a matrix substance will strongly infl uence the MS
profi le, and hence a range of matrices has to be tested to obtain
sensitivity for different classes of compounds. Image capture of
larger tissue sections in high resolution mode generates a vast
amount of spectra, and tools for evaluation are central in the pro-
cessing of the data sets.
