Mass spectrometry
The Unit is well equipped with mass spectrometers of various designs to allow us to carry out a range of experiments on both proteins and small molecules.
Applied Biosystems 4800 Plus MALDI-TOF-TOF
A tandem mass spectrometer with two time of flight (TOF) mass analysers and sample ionisation by MALDI (matrix assisted laser desorption ionisation). This instrument is used primarily for the high resolution analysis of peptide mixtures for protein identification, a part of proteomics. In this application, partial amino acid sequence data and high accuracy measurements of peptide masses are used to identify proteins after electrophoretic separation and thus relate patterns of bands or protein spots to known protein sequences in databases. The instrument is capable of both rapid analyses and high sample throughput.
Applied Biosystems/MDS Sciex Model 4000 Q-TRAP
An electrospray tandem mass spectrometer with a linear ion trap as one of its mass analysers. Coupled to a capillary hplc system, the Q-TRAP spectrometer aids the characterisation of post-translational modifications of proteins, and also helps us to detect differences between protein sequences and corresponding entries in protein sequence databases. A variety of selective analyses based upon diagnostic masses obtained from peptide fragments are used to isolate modified peptides and localize their modifications.
Micromass/Waters Q-TOF1
An electrospray ionisation tandem mass spectrometer with quadrupole and time of flight mass analysers. It is employed in the identification of proteins by capillary liquid chromatograhy (lc) ms-ms analyses of peptide mixtures from proteolytic digests, and also for protein mass measurements and for tandem MS analysis of protein ions.
Micromass/Waters Quattro Ultima
A triple quadrupole mass spectrometer with electrospray ionisation. It is used for lc-ms applications relating to protein analyses, for example, for the separation and molecular mass measurements of intact proteins, and for quantitative assays of triphenyl phosphonium ions and related compounds.
Thermo Orbitrap XL ETD
Our most recent acquisition. It contains a new type of mass analyzer (an OrbiTrap or ‘Makarov’ type mass analyzer) capable of mass measurements with both extremely high resolution and mass accuracy, on a millisecond time scale. It is coupled to a Proxeon ‘Easy’ nanoLC system for nano-scale liquid chromatography of peptide mixtures. These features allow protein mixtures of high complexity to be analysed comprehensively, and for protein abundances to be quantified from samples that have been isotopically labelled (SILAC). The instrument also has an electron transfer dissociation (ETD) option, providing an alternative method for producing peptide fragments via radical ions. ETD is useful for the examination of unstable protein modifications such as phosphorylation.