Combined in-gel tryptic digestion and CNBr cleavage for the generation of peptide maps of an integral membrane protein with MALDI-TOF mass spectrometry.
A limitation of the in-gel approaches for the generation of peptides of membrane proteins is the size and hydrophobicity of the fragments generated. For membrane proteins like the lactose transporter (LacS) of Streptococcus thermophilus, tryptic digestion or CNBr cleavage yields several hydrophobic fragments larger than 3.5 kDa. As a result, the sequence coverage of the membrane domain is low when the in-gel tryptic-digested or CNBr-cleaved fragments are analyzed by matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry (MS). The combination of tryptic digestion and subsequent CNBr cleavage on the same gel pieces containing LacS approximately doubled the coverage of the hydrophobic membrane domain compared to the individual cleavage methods, while the coverage of the soluble domain remained complete. The fragments formed are predominantly below m/z 2500, which allows accurate mass measurement.
Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Bart A
BA
van Montfort
Mark K
MK
Doeven
Benito
B
Canas
Liesbeth M
LM
Veenhoff
Bert
B
Poolman
George T
GT
Robillard
D000595:Amino Acid Sequence; D003488:Cyanogen Bromide; D029968:Escherichia coli Proteins; D005782:Gels; D057927:Hydrophobic and Hydrophilic Interactions; D008565:Membrane Proteins / Q000737:chemistry*; D026901:Membrane Transport Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D010449:Peptide Mapping / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013291:Streptococcus / Q000737:chemistry*; D027981:Symporters; D014357:Trypsin
D029968:Escherichia coli Proteins; D005782:Gels; C050221:LacY protein, E coli; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D027981:Symporters; C021499:lactose permease; D014357:Trypsin; D003488:Cyanogen Bromide