Characterizing changes in snow crab ( Chionoecetes opilio) cryptocyanin protein during molting using matrix‐assisted laser desorption/ionization mass spectrometry and tandem mass spectrometry

• Published in: Rapid Communications in Mass Spectrometry
• Main Authors: Demian, Wael L. L., Jahouh, Farid, Stansbury, Don, Randell, Edward, Brown, Robert J., Banoub, Joseph H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2013
• Subjects: Chionoecetes opilio; Snow crab
• Online Access: http://dx.doi.org/10.1002/rcm.6788; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Frcm.6788; http://onlinelibrary.wiley.com/wol1/doi/10.1002/rcm.6788/fullpdf

RATIONALE We report the matrix‐assisted laser desorption/ionization mass spectrometric (MALDI‐MS) characterization of the cryptocyanin proteins of the juvenile Chionoecetes opilio crabs during their molting and non‐molting phases. In order to assess the structural cryptocyanin protein differences between the molting and non‐molting phases, the obtained peptides were sequenced by MALDI low‐energy collision‐induced dissociation tandem mass spectrometry (CID‐MS/MS). METHODS The cryptocyanin protein was isolated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) and analyzed by MALDI‐TOF/TOF‐MS. The purified cryptocyanin protein was sequenced, using the 'bottom‐up' approach. After tryptic digestion, the peptide mixture was analyzed by MALDI‐QqTOF‐MS/MS and the data obtained were used for the peptide mass fingerprinting (PMF) identification by means of the Mascot database. RESULTS It was demonstrated using MALDI‐TOF/TOF‐MS that the actual molecular weights of the non‐molting and molting cryptocyanin proteins were different; these were, respectively, 67.6 kDa and 68.1 kDa. Using low‐energy CID‐MS/MS we have sequenced the trytic peptides to monitor the differences and similarities between the cryptocyanin molecular structures during the molting and non‐molting stages. CONCLUSIONS We have demonstrated for the first time that the actual molecular masses of the cryptocyanin protein during the molting and non‐molting phases were different. The MALDI‐CID‐MS/MS analyses allowed the sequencing of the cryptocyanins after tryptic digestion, during the molting and non‐molting stages, and showed some similarities and staggering differences between the identified cryptocyanin peptides. Copyright © 2013 John Wiley & Sons, Ltd.