Gln-Gly cleavage: correlation between collision-induced dissociation and biological degradation.
Tryptic digestion of the 150-residue human acidic salivary proline-rich protein 1 (PRP-1) generated eight peptides, two of which corresponded to the N-terminal 30-residue segment. In each of the other six tryptic peptides, a consensus repeat with the structure PQGPPQQGG was present. A facile Gln-Gly cleavage between the second and the third residues of the repeat was observed during collision-induced dissociation experiments. We postulate possible mechanisms to account for this reactivity, involving attack on the peptidyl carbonyl group by the Gln sidechain. Significantly, the Gln-Gly cleavage has been shown to be biologically important in the bacterial degradation of PRPs in saliva, generating bacteria-binding Pro-Gln C-termini. We suggest a link between the gas-phase chemistry and the biochemical degradation of these molecules.
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden. andreas.jonsson@mbb.ki.se
A P
AP
Jonsson
T
T
Bergman
H
H
Jörnvall
W J
WJ
Griffiths
P
P
Bratt
N
N
Strömberg
D000595:Amino Acid Sequence; D004151:Dipeptides / Q000737:chemistry*; D005973:Glutamine / Q000737:chemistry; D005998:Glycine / Q000737:chemistry; D006801:Humans; D006868:Hydrolysis; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification; D055232:Proline-Rich Protein Domains; D012471:Salivary Proteins and Peptides / Q000737:chemistry*; D014357:Trypsin
D004151:Dipeptides; D010446:Peptide Fragments; D010455:Peptides; D012471:Salivary Proteins and Peptides; D005973:Glutamine; D014357:Trypsin; D005998:Glycine