Mobility may reflect covalent modifications, proteolytic processing, or glycosylation Proteomics approaches Differences between proteomics and genomics. Amounts of any given protein depend on tissues and times. Look at arrayed material, but identity of spots unknown. As a result of processing, protein sequence may appear in more than one spot. Database Searches Mass spectrometry Principles and instrumentation.
Proteins are prior-digested with trypsin to give peptides.
The digested protein is imbedded in organic matrix and dried on a surface. Measure the ion current as a function of time. Fragmented peptides can be analyzed by second MS to determine the peptide amino acid sequence. 0.0561 0.0496 Predict Cleavages Fragment matching Proteins are represented by experimental sizes of the peptide fragments generated from them. With a given level of mass accuracy, one can compare the observed sizes to in silico digests of proteins in the protein databases or to polypeptide fragments prediced from sequences in the EST databases.