Detection and sequencing of new cyclic peptides from linseed by electrospray ionization mass spectrometry.
Extract of Linum usitatissimum seeds was analyzed by ESI-MS and ESI-MS/MS. The analysis confirms the presence of previously reported cyclolinopeptides: CLA (c(Pro-Pro-Phe-Phe-Leu-Ile-Ile-Leu-Val) and CLB (c(Pro-Pro-Phe-Phe-Val-Ile-Met-Ile-Leu)). Cyclolinopeptides CLD and CLE, which contain methionine oxide, were detected in small quantities only. These peptides likely result from the oxidation of their precursors, not reported previously: CLD' (c(Pro-Phe-Phe-Trp-Ile-Met-Leu-Leu)) and CLE'(c(Pro-Leu-Phe-Ile-Met-Leu-Val-Phe)), present at higher concentrations in unoxidized extract. Two new cyclic octapeptides: CLF (c(Pro-Phe-Phe-Trp-Val-Met-Leu-Met)) and CLG (c(Pro-Phe-Phe-Trp-Ile-Met-Leu-Met)) were detected and their sequences were proposed on the basis of CID experiments and similarity with those of CLD'.
Stefanowicz
P
P
Faculty of Chemistry, University of Wrocław, Poland. stp@wchuwr.chem.uni.wroc.pl
D019597:Flax / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation / Q000379:methods*
D010455:Peptides