MS analysis of intact proteins and peptides
Suitable for pure samples, this service provides a molecular mass for the protein or peptide of interest.
Samples are processed intact (no enzyme digestion). Depending on the size of the molecule and mass accuracy required MALDI-TOF MS and/or LC/MS is used.
For a RMM <6000amu MALDI-TOF is recommended, and >6000amu LC/MS is preferred.
Mass spectrometry (MS/MS) sequencing MALDI and Electrospray
High sensitivity
mass spectrometry, using the most sophisticated instrumentation (TOF-TOF and LC/MS/MS) is exclusively
used for precise analyses.
Pure protein sample is digested and run through an extended 1- or 2-D LC gradient, and the eluent spotted directly onto a plate for MALDI-TOF/TOF analysis, or infused into the electrospray MS.
For protein sequencing by tandem MS (matrix-assisted laser desorption ionisation time-of-flight - MALDI-TOF/TOF or electrospray ionisation MS/MS), protein samples are enzymatically digested to produce fragmented peptides. Spectra are obtained for alll peptide ions in MS mode and sequence data obtained when the spectrometers automatically revert to MS/MS mode. These spectra are then aligned to the putative sequence for confirmation of protein integrity.
Disulphide Bridge Analysis
This technique is used to characterise disulphide folding pattern, ie an analysis of which Cys residues are linked.
Scope of work:
a) Confirmation of Protein identification by MS
Unambiguous identification is provided using our standard MS/MS sequencing service.
b) Identification of location of di-sulphide bonds.
Full protein characterisation will be performed using our high-end ESI-MS and MALDI TOF/TOF instruments. The analysis will look for di-sulphide bonded peptide fragments following enzyme digestion of the protein.
For analysis we require the full theoretical protein sequence, and postulated S-S bridging patterns.
Techniques used include HPLC or Multiple reaction monitoring
Multiple reaction monitoring is a highly specific and sensitive mass spectrometry technique that can selectively quantify compounds within complex mixtures.
This service is also used for biomarker analysis and reaction monitoring in
pharmacokinetic studies for toxic metabolites.
For more information please refer to Proteomics International publication and application notes.
Click here to read more about MRM - Multiple Reaction Monitoring