Sampling the N-terminal proteome of human blood

摘要: The proteomes of blood plasma and serum represent a potential gold mine biological diagnostic information, but challenges such as dynamic range protein concentration have hampered efforts to unlock this resource. Here we present method label isolate N-terminal peptides from human serum. This process dramatically reduces the complexity sample by eliminating internal peptides. We identify 772 unique in 222 proteins, ranging over six orders magnitude abundance. approach is highly suited for studying natural proteolysis find cleavages proteins created endo- exopeptidases, providing information about activities proteolytic enzymes blood, which may be correlated with disease states. also signatures signal peptide cleavage, coagulation complement activation, other known processes, addition large number that not been reported previously, including 200 aminopeptidases. Finally, can substrates specific proteases exogenous protease combined isolation quantitative mass spectrometry. In way identified cleaved membrane-type serine 1, an enzyme linked cancer progression. These studies demonstrate utility direct labeling subtiligase characterize endogenous