Glycine-containing flaxseed orbitides.

Five new orbitides, cyclolinopeptides 21–25, were identified in flaxseed oil (Linum usitatissimum) extracts. Their HPLC-ESIMS quasimolecular ion peaks at m/z 1097.7 (21), 1115.6 (22), 1131.6 (23), 1018.6 (24), and 1034.6 (25) [M + H]+ corresponded to the molecular formulae C59H89N10O10, C58H87N10O10S, C58H87N10O11S, C53H80N9O9S, and C53H80N9O10S, respectively. Their structures were elucidated by extensive HPLC-ESIMS/MS analyses, and their presence was confirmed by precursor proteins identified in flax genomic DNA sequence data. The amino acid sequences of these orbitides were confirmed as [1–10-NαC]-GILVPPFFLI, [1–10-NαC]-GMLIPPFFVI, [1–10-NαC]-GOLIPPFFVI, [1–9-NαC]-GMLVFPLFI, and [1–9-NαC]-GOLVFPLFI for cyclolinopeptides 21–25, respectively. Previously reported orbitides, [1–9-NαC]-ILVPPFFLI (1), [1–9-NαC]-MLIPPFFVI (2), [1–9-NαC]-OLIPPFFVI (3), [1–8-NαC]-MLVFPLFI (7), and [1–8-NαC]-OLVFPLFI (8), were also present in flaxseed oil. The precursors of orbitides 21, 22, and 24 also produced orbitides 1, 2, a...