Differential in vitro inhibition of polyphenoloxidase from a wild edible mushroom Lactarius salmonicolor

Figures & data

Figure 1.  Purification of LsPPO by elution from the affinity gel.

Figure 2.  V_MAX and K_M values of LsPPO with (a) catechol; (b) 4-methyl catechol; (c) pyrogallol substrates.

Table I.  Purification of polyphenol oxidase from Lactaris salmonicolor.

Steps	Volume (mL)	Activity (U/mL)	Total Protein (mg)	Protein (mg/mL)	Total Activity (U)	Specific Activity (U/mg)	Purification fold	Overall Yield (%)
Crude Extract	87	6425	120.1	1.38	558975	4654.2	–	100
Ammonium sulphate precipitation	60	4975	16.2	0.27	298500	18425.9	3.96	34.2
Dialysis	10.8	9450	18.8	1.74	102060	5428.7	1.17	18.3
Affinity chromatography	3	13000	0.315	0.105	39000	123809.5	26.6	7

Figure 3.  (a) The effect of temperature on the purified LsPPO activity; (b) Effect of pH on the activity of LsPPO with different substrates.

Table II.  Effects of inhibitors on LsPPO.

Inhibitor	Type of inhibition	Ki (M)	IC50 (M)
L-cysteine	Uncompetitive	1.45 × 10^− 5	1.5 × 10^−4
L-tyrosine	Uncompetitive	1.75 × 10^− 3	3.8 × 10^−7
Glutathione	Mixed type(Competitive + non competitive)	K1: 0.067 × 10^− 5 < K2: 1.6 × 10^− 5	9.1 × 10^−4
p-aminobenzenesulfonamide	Competitive	2.67 × 10^− 5	2.3 × 10^−4
Oxalic acid	Uncompetitive	7.43 × 10^− 8	1.2 × 10^−4
β-mercapto-ethanol	Uncompetitive	0.31 × 10^− 5	4.9 × 10^−4
Syringic acid	Uncompetitive	2.14 × 10^− 5	4 × 10^−4