Integrated microchip-device for the digestion, separation and postcolumn labeling of proteins and peptides

A microchip device was demonstrated that integrated enzymatic reactions, el ectrophoretic separation of the reactants from the products and post-separa tion labeling of proteins and peptides prior to detection. A tryptic digest ion of oxidized insulin B-chain was performed in 15 min under stopped flow conditions in a heated channel, and the separation was completed in 1 min. Localized thermal control of the reaction channel was achieved using a resi stive heating element. The separated reaction products were then labeled wi th naphthalene-2,3-dicarboxaldehyde (NDA) and detected by laser-induced flu orescence. A second reaction at elevated temperatures was also demonstrated for the on-chip reduction of disulfide bridges using insulin as a model pr otein. This device represents one of the highest levels, to date, of monoli thic integration of chemical processes on a microchip. (C) 2000 Elsevier Sc ience B.V. All rights reserved.