Peptidomics: identification and quantification of endogenous peptides in neuroendocrine tissues

Neuropeptides perform a large variety of functions as inter- cellular signaling molecules. While most proleomic studies involve digestion of the proteins with trypsin or other proteases, peptidomics studies usually analyze the native peptide forms. Neuropeptides can be studied by using mass spectrometery for identification and quantitation. In many cases, mass spectrometry provides an understanding of the precise molecular form of the native peplide, including post-translational cleavages and other modifications. Quantitative peptidomics studies generally rise differential isotopic tags to label two sets of extracted peptides, as done with proteomic studies, except that the Cys- based reagents typically used for quantitation of proteins are not suitable because most peptides lack Cys residues. Instead, a number of amine-specific labels have been created and some of these are useful for peptide quantitation by mass spectrometry. In this review, peptidomics techniques are discussed along with the major findings of many recent studies and future directions for the field. (c) 2006 Wiley Periodicals, Inc.