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New flaxseed orbitides: Detection, sequencing, and 15 N incorporation
Author(s) -
OkinyoOwiti Denis P.,
Young Lester,
Burnett PetaGaye G.,
Reaney Martin J. T.
Publication year - 2014
Publication title -
peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.22459
Subject(s) - chemistry , linum , electrospray ionization , tandem mass spectrometry , mass spectrometry , genome , dna , peptide , computational biology , chromatography , gene , biochemistry , biology , botany
Three new orbitides (cyclolinopeptides 17 , 18 , and 19 ) were identified in flaxseed (Linum usitatissimum L.) extracts without any form of purification. Their structures were elucidated by a combination of 15 N‐labeling experiments and extensive tandem mass spectrometry (MS/MS) with electrospray ionization (ESI). Putative linear peptide sequences of the new orbitides were used as the query in the Basic Local Alignment Search Tool (BLAST) searches of flax genome database. These searches returned linear sequences for the putative precursors of cyclolinopeptides 17 and 19 among others. Cyclolinopeptide 18 contains MetO (O) and is not directly encoded, but is a product of post‐translation modification of the Met present in 17 . The identification of precursor proteins in flax mRNA transcripts and DNA sequences confirmed the occurrence and amino acid sequences of these orbitides as [1–9‐NαC]‐MLKPFFFWI, [1–9‐NαC]‐OLKPFFFWI, and [1–9‐NαC]‐GIPPFWLTL for cyclolinopeptides 17 , 18 , and 19 , respectively. © 2014 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 102: 168–175, 2014.