Direct measurement of ascorbic acid biosynthesis in Arabidopsis cell suspension culture using capillary electrophoresis.

We describe procedures to directly measure the biosynthesis of vitamin C (L-ascorbic acid, L-AA) in crude extracts of an Arabidopsis thaliana cell suspension culture by capillary electrophoresis. Optimal conditions have been established for the quantitation of L-AA formed by the oxidation of three different substrates: L-galactose, L-galactono-1,4-lactone, and L-gulono-1,4-lactone. We also demonstrate that L-galactono-1,4-lactone dehydrogenase activity does not require exogenous cofactor. The minimal sample handling requirements, the high selectivity, and short analysis times represent significant advantages over existing protocols.