In this Article, we have reported a fully automated online method to carry out proteolysis and glycopeptide enrichment in sequence for nanoflow liquid chromatography-tandem mass spectrometry (nLC-ESI-MS/MS) analysis. By implementing two serial thermoresponsive porous polymer membrane reactors (TPPMRs), in which the TPPM could be immobilized either with trypsin for proteolysis or with lectins for glycopeptide enrichment, the entire pretreatment procedure can be performed online in about an hour. The TPPM was fabricated by coating polystyrene-maleic anhydride-N-isopropylacrylamide (PS-MAn-PNIPAm), which was synthesized by reversible addition-fragmentation chain transfer polymerization, on a Nylon sheet. Because of the thermoresponsive nature of PNIPAm, it formed micelle cavities and changed its morphology at elevated temperatures, resulting in enhanced interactions between the enzyme or lectins and the proteins/peptides flowing through the membrane. The performances of the TPPMs were evaluated by varying the temperature conditions and the amount of standard proteins, showing that both proteolysis and glycopeptide enrichment with online deglycosylation were highly efficient at 37 °C. The developed online serial TPPMRs-nLC-ESI-MS/MS method was applied to the human plasma sample (1.5 μL) and a total of 262 N-glycopeptides could be identified from 155 glycoproteins. Thus, the present work demonstrates a fully automated high speed analytical protocol for online proteolysis and glycopeptide enrichment, which is extremely useful for analyzing small amounts of the proteome samples.
Bibliographical noteFunding Information:
This study was supported by the bilateral research program between China and Korea: Grant No. 21611540335 from the National Natural Science Foundation of China (NSFC) and NRF-2016K2A9A2A06004726 from the National Research Foundation (NRF) of Korea. This work was also supported in part by NRF-2015R1A2A1A01004677 and NSFC-21475137, -21635008, -21621062.
© 2018 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Analytical Chemistry