The GeLC-MS/MS express service enables identification of proteins in gel bands present at low to sub-nanogram quantities. Protein which can be visualized by Coomassie brilliant blue staining or silver staining can almost always be positively identified by GeLC-MS/MS. Turn-around time is about one week for small sample sets. Please inquire for larger sample sets. Starting from $100 per sample.
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Samples are processed upon arrival and placed in a queue for UPLC-MS/MS. Samples are analyzed on a first-come, first-served basis. Typical turn-around time is about one week.
All Coomassie dyes and silver stains marketed as “MS-compatible” will work. Non-“MS-compatible” silver stains will also work, though there can be a decrease in sensitivity. Let us know if you have used a non-compatible silver stain and we will take steps to enhance protein recovery.
Bands which can be visualized by Coomassie Brilliant Blue stain are almost always identifiable. Bands visualized by silver stain are usually identifiable. The exceptions are typically very low abundance, low molecular weight proteins near the limit of detection of the silver stain and with few observable peptides. A Western blot is not a good indicator of suitability for LC-MS/MS.
Any species with an available sequence library (FASTA file) can be assayed. If a sequence library is not available for a species or if the library is limited in scope, we can attempt to search a library of related species to search for homologous proteins. There is no extra charge for searching a custom sequence library. We support all UniProt libraries by default. Search UniProt taxonomies to see if your organism is present.
Some MALDI-TOF/TOF instruments do have excellent sensitivity (the Q-Exactive has sub-femtomole LOD). For MALDI-based analyses the peptides resulting from the in-gel digestion are typically spotted to a single target well on the MADLI plate. The entire spot is then ionized for TOF/TOF analysis. This means that the ionization energy is divided between all of the peptides in the sample and the detector has to attempt to sequence all the peptides on a very limited time scale - on the order of seconds. For LC-ESI-based analyses the peptides are chromatographically resolved (separated from each other) over the course of the gradient. The benefit of this is three-fold:
Perform a very short-run SDS-PAGE separation: