Sequence determination by MALDI-TOF mass spectrometry of an insecticidal lentil peptide of the PA1b type.

Taylor, W.G., Sutherland, D.H., Zhang, H., and Hegedus, D.D. (2015). "Sequence determination by MALDI-TOF mass spectrometry of an insecticidal lentil peptide of the PA1b type.", Phytochemistry Letters, 12, pp. 105-112. doi : 10.1016/j.phytol.2015.03.003  Access to full text

Abstract

Mature seeds of lentil (Lens culinaris Medik.) were previously reported to contain an insecticidal cysteine-rich peptide, likely of the albumin-1 subunit b type. The purpose of this work was to determine the amino acid sequence of this insecticidal lentil peptide in an Eston lentil extract by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), after reduction of the disulfide bridges, alkylation of the cysteine residues and hydrolysis by pronase, trypsin, chymotrypsin and endoproteinase Asp-N. Sequences of key fragments were supported by monoisotopic mass measurements and by sequence ions from collision-induced dissociation (CID) experiments with a MALDI-TOF/TOF analyzer (MS/MS analysis). The new 37 amino acid sequence revealed strong similarities to a histidine-containing pea PA1b peptide and to soybean leginsulins but with a unique segment of RSSA in the middle. The lentil PA1b peptide sequence agreed completely with that derived from a L. culinaris genomic DNA sequence.

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