Biosynthesis of cyclopentenylglycine from α-ketopimelate in Idesia polycarpa callus cultures.

The nonproteinogenic amino acid, cyclopentenylglycine, is found in certain Flacourtiaceae. This compound may be synthesized by two C1-chain elongations of α-ketoglutarate via α-ketopimelate (C5+2C1) or by condensation of C4 and C3 units (C4+C3), a pathway not involving α-ketopimelate. The following experimental design elucidated the biosynthetic pathway: Idesia polycarpa callus cultures were freshly established from leaf petioles; synthetic α-[1,2-(14)C]ketopimelate was added to the medium and cultures were incubated for 3 weeks. After isolation and separation of free amino acids from the tissues, the radioactivity incorporated into cyclopentenylglycine was determined. The results establish α-ketopimelate as a precursor for cyclopentenylglycine, thus providing evidence for the C5+2C1 biosynthetic path.