The browning related enzymes in mango skin were investigated.Crude proteins were extracted from mango juicing with centrifugation,filtration and concentration methods and purified by column chromatography.Two isoenzymes,P1 and P2,were purified.Using catechol as substrate,the activity of the enzyme was determined by spectrophotometry at 420 nm.The results showed that the optimal temperature,pH value,substrate for mango P1 was 55℃,7.0,and catechol,respectively.The molecular weight of P1 was 100 ku.The activity of P2 was very low.Results of circular dichroism showed that the content of αhelix and βfold of the two enzyme was 32.1% and 19.2%,43.4% and 80.8%,respectively.Result of fluorescence excitation spectra showed that the maximum emission wavelength of P1 and P2 was at 358.4 nm and 356 nm with the fluorescence intensity of 207.9 and 164.2.The particle size distribution of the two enzymes was more concentrated at 11.696 nm and 8.721 nm,reaching 29.686% and 25.369%.