Chapter 2 : Introduction to Protein Analysis

Abstract:

There are multiple sources of variation in individual proteins and in the proteome. Posttranslational modifications of the primary translation products of mRNAs potentially lead to large numbers of structural variants of individual gene products. As proteins undergo extracellular and intracellular degradation, a complex array of peptides is generated, quite possibly even more complex than the original set of proteins. Peptide splicing has recently been identified as another mechanism that may increase peptide diversity. In order to understand many pathophysiological processes, such as prion diseases, amyloidosis, hemoglobinopathies, and apoptotic processes, simple primary sequence analysis of proteins is inadequate. Two additional challenges to protein analysis that are nearly as great as structural diversity are (i) the dynamic nature of protein concentration and (ii) the wide range of protein concentrations. Unlike the case for nucleic acids, there is no simple method for amplification of the concentration of proteins. Most methods for protein analysis have a practical analytical concentration range of only about 100to 10,000-fold, and the highest-resolution separation methods for protein analysis, such as two-dimensional gel electrophoresis, have the capability of resolving only up to a few thousand components in a single analysis.