Green synthesis of monolithic enzyme microreactor based on thiol-ene click reaction for enzymatic hydrolysis of protein.

In this study, a monolithic enzyme reactor based on a strategy of green synthesis was successfully prepared in a capillary with trypsin immobilized by "thiol-ene" click reaction. A polymer of poly(butyl methacrylate-co-α-methacrylic acid-co-ethylene glycol dimethacrylate) was prepared in a mixture of 1-butyl-3-methylimidazolium tetrafluoroborate and choline chloride/ethylene glycol as the support of enzyme reactor. After "thiol-ene" reaction was used for enzyme immobilization, the Michaelis constants and maximum reaction rate of the resulting immobilized enzyme reactors (IMER) were determined by capillary electrophoresis to be 2.1 mmol/L and 0.028 μmol/min, respectively. The enzymatic hydrolysis of the enzyme reactor under different experimental conditions were investigated. A on-line digestion of bovine serum albumin (BSA) on the new IMER can be achieved within 50 s, up to 864 times faster than in-solution digestion (12 h). BSA can be well digested and the numbers of identified peptides were 73 with the coverage rates of 82.7%. The IMER was further used for the analysis of protein extracts from rat liver, and 1034 protein groups were identified. All these results demonstrated that such a click reaction based IMER would be of great prospect in the high throughput analysis for proteome with high confidence.