Table 1.

RSZD and strain energies (ΔE_str, kJ mol⁻¹) for the various QM-refined structures in the three protomers 1–3.

PDB[a]	Structure[b]	State[c]	RSZD			ΔEstr
			1	2	3	1	2	3
3RGB	C2W0	Red	2.1	2.8	2.0	179	195	176
		MV	1.9	2.9	2.6	224	178	160
		Ox	2.1	2.9	2.8	300	247	224
	Y2W2	Red	3.2	2.2	3.0	153	144	160
		MV	1.5	1.9	3.2	149	110	104
		Ox	1.5	2.1	2.9	158	126	104
	Y2W0	Red	2.7	2.5	1.8	220	226	227
		MV	1.3	2.7	2.1	170	136	124
		Ox	1.3	2.8	2.2	214	179	167
	C1W0	Red	1.7	1.1	1.5	85	62	76
		Ox	1.6	1.7	1.6	75	47	37
	C1W1	Red	1.7			90
		Ox	1.5	2.4	2.0	64	53	52
3RFR	C2W0	Red	2.7			311
		MV	1.6			292
		Ox	1.9			357
	C1W0	Red	1.4	0.4	0.9	88	101	89
		Ox	1.3	0.4	0.9	32	47	37
	C1W1	Red	2.6			82
		Ox	2.3	1.3	1.0	42	68	58

^[a]PDB code.

^[b]Number of Cu ions (C2 or C1; Y2 represents planar structures, see Figure 3) and number of water molecules, W0–W2.

^[c]Oxidation state of the Cu ion(s), fully reduced (Red), oxidised (Ox), or mixed valence (MV; Cu^I+Cu^II).