Identification and characterization of microbial proteins using peptide mass fingerprinting strategies

Peptide mass fingerprinting is a simple, quick, cheap, and relatively effective method of identifying proteins from mass spectrometry data. Proteins extracted from the complex mixture comprising the proteome of a sample are individually digested with a proteolytic enzyme into a series of peptide fragments. The set of masses of these peptides, determined by mass spectrometry, form a peptide mass fingerprint of the protein. Comparison of this experimental fingerprint with the theoretical fingerprints of all known protein sequences for this organism, derived computationally from a protein sequence database, allows the identification of the particular protein. In this chapter, I discuss the technique including preparation for the peptide mass fingerprinting analysis, the appropriate selection of computational search parameters, and the analysis and interpretation of search results in the context of identifying proteins from microbial samples.