The time course of the enzyme catalysed transhydrocyanation of benzaldehyde to give (S)-mandelonitrile was
investigated using a hydroxynitrile lyase from Hevea brasiliensis as catalyst and acetone cyanohydrin as cyanide
donor. Employing special techniques it was possible to apply ~H NMR spectroscopy in aqueous medium to monitor
the concentration changes of all substrates and products. By this technique strong evidence for inhibition of the
enzyme at higher substrate concentrations was obtained.