Partial Purification and Characterization of an Auxin-Degrading Enzyme in the Liverwort Marchantia polymorpha L.

A buffer-polyvinylpyrolidone extract of Marchantia polymorpha, purified by ammonium sulfate fractionation and dialysis, degraded indole-3-acetic acid (IAA) in vitro. Enzyme activity was optimal at pH 5.5-60, was stimulated by 2,4-dichlorophenol (DCP) and MnCl2, and inhibited by KCN. Sodium bisulfite enhanced the reaction at low concentrations and inhibited it at higher concentrations. The duration of a characteristic lag phase depended on the pH, substrate concentration, and presence. of natural inhibitors. Relations to other auxin oxidase systems are discussed.