Diagnosis of cellular states of microbial organisms using proteomics

Two-dimensional (2-D) polyacrylamide gel electrophoresis has much to contri bute to experimental analysis of the proteomes of microbial organisms, sinc e this method separates most cellular proteins and allows synthesis rates t o be determined quantitatively. Databases generated using 2-D gels can grow to be very large from even just a few experiments, since each sample provi des the data for a field (or column) in the database for several hundreds t o even thousands of records (or rows), each of which represents a single po lypeptide species. The value of such databases for generating an encycloped ia of how each of the cell's proteins behave in different conditions (prote in phenotypes) has been recognized for some time. The potential exists, how ever, to glean even more valuable information from such databases. Because the measurements of each protein are made in the context of all other prote ins, a comprehensive glimpse of the cell's physiological state is theoretic ally achievable with each 2-D gel. By examining enough conditions (and 2-D gels), expression patterns of subsets of proteins (proteomic signatures) ca n be found that correlate with the cell's state. This type of information c an provide a unique contribution to proteomic analysis, and should be a maj or focus of such analyses.