Partial purification, characterization, and histochemical localization of fully latent desert truffle (Terfezia claveryi Chatin) polyphenol oxidase

In the present paper, a fully latent polyphenol oxidase (PPO) from desert t ruffle (Terfezia. claveryi Chatin) ascocarps is described for the first tim e. The enzyme was partially purified by using phase partitioning in Triton X-114 (TX-114) The achieved purification was 2-fold from a crude extract, w ith a 66% recovery of activity. The interfering lipids were reduced to 13% of the original content. In addition, the purification gave rise to a reduc tion bf phenolic compounds to only 37.5%, thus avoiding the postpurificatio n tanning of the enzyme. Latent PPO was activated by the anionic surfactant sodium dodecyl sulfate (SDS) or by incubation with trypsin. The amount of SDS necessary to obtain a maximum activation was dependent on the nature of the substrate. The use of SDS also permitted the histochemical localizatio n of the latent enzyme within the ascocarp. Terfezia polyphenol oxidase was kinetically characterized using two phenolic substrates (L-DOPA and tert-b utylcatechol). The latter substrate presented inhibition at high substrate concentration with a K-si of 6.3 mM. Different inhibiting agents (kojic and cinnamic acid, mimosine and tropolone) were also studied, tropolone being the most effective.