Table 5.

Summary of the mutations to the second activity controller residue: effects on PPOs′ copper content and diphenolase/monophenolase activity. The modification of copper content and the rate of activity are described compared to the wild type of the corresponding enzymes.

Second activity controller (HisB2+1)
Enzyme	Mutant	Diphenolase activity	Monophenolase activity	Copper %	Ref.
BmTYR	Arg209His	−1.5‐fold (l‐DOPA: 7.18 s−1) ∼same (d‐DOPA: 6.88 s−1)	+1.7‐fold (l‐tyrosine: 2.24 s−1)	n.i.	[78]
ToPPO2	Ile244Arg	−1.77‐fold (4‐methylcatechol: 140 s−1) −4.14‐fold (catechol: 17.6 s−1) −3.12‐fold (dopamine: 66.5 s−1) −2.2‐fold (DOPAC: 85.2 s−1)	n.i.	n.i.	[77]
ToPPO6	Arg254Ile	−1.61‐fold (4‐methylcatechol: 310 s−1) −1.87‐fold (catechol: 193 s−1) ∼same (dopamine: 89 s−1) −1.84‐fold (DOPAC: 40 s−1)	n.i.	n.i.
JrPPO1	Leu244Arg	−4.0‐fold (dopamine: 24.9 s−1) −11‐fold (l‐DOPA: 10.5 s−1)	−15‐fold (tyramine: 1.62 s−1)	50	[69]
CgAUS	Arg257Gly	+2.3‐fold (dopamine: 1264 s−1)	n.d.	77	[45]
	Arg257Leu	+4.0‐fold (dopamine: 2245 s−1)	n.d.	65
	Arg257Ile	+3.0‐fold (dopamine: 1660 s−1)	n.d.	66
	Arg257Asp	+2.5‐fold (dopamine: 1380 s−1)	++ (tyramine: 8.26 s−1)	11

n.d.: no detected activity, n.i.: no information from the particular study, ++: generation of monophenolase activity that was not present in the wild type, entries in s^‐1 refer to k_cat values.