title: Glycine-containing flaxseed orbitides.
abstract: 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, and 7 by alternative cyclization. Cyclolinopeptides 3, 8, 23, and 25 contain MetO (O) and are not directly encoded, but are products of post-translational modification of the Met present in 2, 7, 22, and 24, respectively. Sufficient cyclolinopeptide 23 was isolated for characterization via 1D ((1)H and (13)C) and 2D (NOESY and HMBC) NMR spectroscopy. These compounds have been named as cyclolinopeptides U, V, W, X, and Y for 21, 22, 23, 24, and 25, respectively.
authors.affiliation: †Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
authors.forename: Peta-Gaye G
authors.initials: PG
authors.lastname: Burnett
authors.affiliation: †Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
authors.forename: Pramodkumar D
authors.initials: PD
authors.lastname: Jadhav
authors.affiliation: †Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
authors.forename: Denis P
authors.initials: DP
authors.lastname: Okinyo-Owiti
authors.affiliation: ‡Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Aaron G
authors.initials: AG
authors.lastname: Poth
authors.affiliation: †Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.|§Guangdong-Saskatchewan Oilseed Joint Laboratory, Department of Food Science and Engineering, Jinan University, Guangzhou, Guangdong 510632, People's Republic of China.
authors.forename: Martin J T
authors.initials: MJ
authors.lastname: Reaney
mesh_terms: D000595:Amino Acid Sequence; D003500:Cyclization; D019597:Flax / Q000737:chemistry*; D005998:Glycine / Q000032:analysis / Q000737:chemistry*; D008043:Linseed Oil / Q000737:chemistry* / Q000302:isolation & purification*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010456:Peptides, Cyclic / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D010456:Peptides, Cyclic; D008043:Linseed Oil; D005998:Glycine