The extent and effects of peptide sequence scrambling via formation of macrocyclic B ions in model proteins.
The extent and effects of sequence scrambling in peptide ions during tandem mass spectrometry (MS/MS) have been examined using tryptic peptides from model proteins. Sequence-scrambled b ions appeared in about 35% of 43 tryptic peptides examined under MS/MS conditions. In general, these ions had relatively low abundances with averages of 8% and 16%, depending on the instrumentation used. A few tryptic peptides gave abundant scrambled b ions in MS/MS. However, peptide and protein identifications under proteomic conditions with Mascot were not affected, even for these peptides wherein scrambling was prominent. From the 43 tryptic peptides that have been investigated, the conclusion is that sequence scrambling is unlikely to impact negatively on the accuracy of automated peptide and protein identifications in proteomics.
Saminathan
Irine S
IS
Department of Chemistry and Centre for Research in Mass Spectrometry, York University, Toronto, Ontario, Canada.
Wang
X Simon
XS
Guo
Yuzhu
Y
Krakovska
Olga
O
Voisin
Sébastien
S
Hopkinson
Alan C
AC
Siu
K W Michael
KW
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D006736:Horses; D047028:Macrocyclic Compounds / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D011506:Proteins / Q000737:chemistry / Q000378:metabolism; D040901:Proteomics / Q000379:methods* / Q000592:standards; D015203:Reproducibility of Results; D020539:Sequence Analysis, Protein / Q000379:methods* / Q000592:standards; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014357:Trypsin / Q000378:metabolism
D047028:Macrocyclic Compounds; D010446:Peptide Fragments; D011506:Proteins; D014357:Trypsin