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MS Protein Identification
MS Protein Identification
This service offers the possibility of
identifying proteins (that are usually submitted as Coomassie Blue
stained gel bands/spots from 1D/2D SDS polyacrylamide gels) following
MALDI-MS of a (usually) small aliquot of the resulting in gel tryptic
digest. The limit of sensitivity is in the 5-50 fmol range (assuming
most of the digest is committed to MALDI-MS) and the resulting
monoisotopic peptide masses are then submitted to one or more peptide
mass search algorithms to identify protein(s) that are present. We have
found that an automated MALDI-MS protein identification (where a
computer algorithm chooses the masses for searching) is not quite as
good as a manual identification, where we chose the masses to search.
For this reason, we are now only offering the manual MALDI-MS protein
identification. The overall success rate for the Manual MALDI-MS
Protein Identification Service is about 40% - with this rate increasing
substantially when the protein derives from an organism whose genome
has been sequenced and well characterized (e.g., S. cerevisiae). As
many as four proteins have been identified by this service in a single,
2D SDS polyacrylamide gel spot. However, protein mixtures can be
challenging for MALDI-MS protein identification and therefore, a
MS/MS approach is highly recommended. SDS
PAGE-separated proteins submitted for in gel trypsin digestion followed
by MS protein identification should be stained as
described with Coomassie Blue
(preferably) or with digestion compatible silver (More Information on the
Manual
MALDI-MS Protein Identification).
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