Table 1. Catalytic Activity of MthUPO Variants for the Hydroxylation of NBD^a.

MthUPO variant	conversion [%]	TOF [min–1]	TON
WT	29	72	4340
L60F	77	194	11,610
L60F/S159G/A161F	84	210	12,590
F59Q/L60M/S159G/F154A	77	192	11,540
F59Q/L60F/S159Gb	76	379	22,760

^aTOF = turnover frequency, TON = turnover number, standard deviation <3.2%, reaction conditions: 20 nM MthUPO variant, 300 μM NBD, 1 mM H₂O₂, 100 mM KPi buffer (pH 7), 5% acetone (v/v), measurement conditions: absorbance was measured at 425 nm for 1 h in triplicates, values were calculated with the corrected extinction coefficient of 10,870 M^–1 cm^–1 (see Figure S2).

^b10 nM MthUPO.