Measurement of relative amounts of phospho- and dephospho-B-50(GAP-43) peptides by fast atom bombardment-mass spectrometry.
The biological role of phosphoproteins depends upon their degree of phosphorylation in vivo. Methods currently available to measure the degree of phosphorylation of a protein involve indirect procedures to detect the 32P-phosphate incorporation. We report here a direct method to measure relative amounts of phospho- and dephospho-forms of peptides based upon a mass spectrometric technique. The intensities of the molecular ions corresponding to the two forms of the peptides are proportional to their relative amounts. This is demonstrated for a peptide fragment of the protein B-50(GAP-43) and for kemptide, respectively substrates for protein kinases C and A, and demonstrates the applicability of fast atom bombardment-mass spectrometry to quantitate peptides bearing post-translational modifications.
Di Luca
M
M
Institute of Pharmacological Sciences, University of Milano, Italy.
de Graan
P N
PN
De Angelis
L
L
Gispen
W H
WH
Cattabeni
F
F
D000595:Amino Acid Sequence; D005069:Evaluation Studies as Topic; D019922:GAP-43 Protein; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000032:analysis* / Q000378:metabolism; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000032:analysis* / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism*; D010750:Phosphoproteins / Q000032:analysis* / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D016339:Spectrometry, Mass, Fast Atom Bombardment / Q000379:methods*
D019922:GAP-43 Protein; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D009842:Oligopeptides; D010750:Phosphoproteins; C037642:kemptide; D011494:Protein Kinases