Purification and characterization of anthocyanin degradation enzyme from litchi fruit pericarp.

摘要

The major limitation in litchi marketing is the rapid lose of the red color after harvest, accompanied by pericarp browning. To investigate the possible anthocyanin degradation mechanisms other than the hypothesis of anthocyanin-PPO/POD-phenols system, in the present study, anthocyanin degradation enzymes (ADEs) were purified from litchi pericarp by ammonium sulfate fractionation, DEAE-Sepharose and Sephadex G-75 chromatography to almost homogenous. The purified ADE showed one major band on SDS-PAGE, with molecular size around 114 kDa. PPO and POD activities were detected in the crude extract of the pericarp, but not in the purified litchi ADE. The purified ADE showed high activity for litchi anthocyanins, mainly cyanidin-rutinside, with apparent Km value 72.7 nmol/L. However, the enzyme showed negligible activity for the anthocyanin substrate prepared from black soybean coat or raised petal, in which the major anthocyanin is cyanidin-glucoside. The results indicate that an unknown protein with anthocyanin decolorization function but no PPO and POD activities were detected in litchi pericarp.