Grass pea seeds and seedlings protein extracts were chromatographically fractionated. To identify the β-ODAP synthase enzyme, active fractions, as determined by a colorimetric assay that detects the presence of a derivative of free L-α,β-diaminopropionic acid (L-DAPA), were subjected to tryptic digestion and LC-MS/MS and searched against a database containing translated sequences from a long-read PacBio mRNA sequencing of grass pea seeds and seedlings.