Table 1.

Designed Metalloenzymes Mimicking Native Protein Metal Active Sites

designed protein	reaction	kcat/s−1	kcat/Km/M−1 s−1	k1, k2/(M−1)s−1	metal coordination and spectroscopic parameters	other notes	ref
PT3.3	DECP hydrolysis	351 (±26) × 10−3	9750 ± 1534		Zn(His)3Asp(OH2/OH−)	(1) kcat, kcat/Km values at pH 7.5; (2) the crystal structure is for PT3.1; same active site	204
					PDB code: 3T1G
MID1-zinc	pNPA hydrolysis	0.30	630(max)a		Zn(His)3(OH2/OH−)	(1) pKa = 8.2 ± 0.1; (2) the crysal structure showed tartrate binding, but the activity supports water/hydroxide binding	211
					PDB code: 3V1C
Hg(II)sZn(II)(H2O/OH−)N(TRIL9CL23H)3	pNPA hydrolysis	~0.053	31 ± 4(max)a		Zn(His)3(OH2/OH−)	(1) pKa = 9.0 ± 0.1; (2) kcat/Km(max) determined by fitting the kcat/Km(max) values vs pH	212,213
					PDB code: 3PBJ
Hg(II)sZn(II)(H2O/OH−)N(TRIL9CL23H)3	CO2 hydration	1.8 (±0.4) × 103	1.8 (±0.5) × 105		Zn(His)3(OH2/OH−)	kcat, kcat/Km values at pH 9.5	213
					PDB code: 3PBJ
Cu(TRI(L2W)L23H)3+/2+	nitrite reduction			k1Asc = 12 ± 3 × 10−4	Cu(I)(His)3 trigonal planar (R(Cu–N) = 1.93 Å); Cu(II) λd–dmax = 640 nm (ε = 138 M−1 cm−1); g|| = 2.27 (A|| = 186 G)	(1) pH-dependent rates; (2) k1Asc at pH 5.3; (3) spectroscopic parameters at pH 7.4	214
di-Fe(III)-DF3	3,5-DTBC oxidation	0.22 ± 0.02	105		di-iron center with an oxo-bridge; ε350 nm = 5270 M−1 cm−1	pH 7.0, 25 °C	215
di-Fe(III)-DF3	4-aminophenol oxidation	0.045 ± 0.003	23.0			pH 7.0, 25 °C	215
G4DFtet	4-aminophenol oxidation	0.022 ± 0.002	25.7			pH 7.0, 25 °C	216
Fe-mimochrome VI	ABTS oxidation	375	8.4 × 10−3 for H2O2; 4.42 for ABTS		pH-dependent Soret band transformation	pH 6.5	217
Fe-MP3	ABTS oxidation	535 ± 42	3.2 × 10−4 for H2O2; 6.4 × 10−8 for ABTS		oxidized form Soret band at 391 nm at pH 4.7 and 6.6	pH 6.5, 40% TFE	218

^aMaximal efficiency from the fitting of k_cat/K_M values versus pH (assuming 100% active enzyme complex is present).