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 sus pension culture by capillary electrophoresis. Optimal conditions have been established for the quantitation of L-AA formed by the oxidation of three d ifferent substrates: L-galactose, L-galactono-1,4-lactone, and L-gulono-1,4 -lactone. We also demonstrate that L-galactono-1,4-lactone dehydrogenase ac tivity does not require exogenous cofactor. The minimal sample handling req uirements, the high selectivity, and short analysis times represent signifi cant advantages over existing protocols. (C) 1999 Elsevier Science B.V. All rights reserved.