Table S1.

Anomalous correlation coefficients (CC_ano) comparing anomalous differences between randomly selected half-datasets

Resolution	CCano, %
	X-ray	Electron
	Zn2+-NNQQNY	Zn2+-NNQQNY	Cd2+-NNQQNY	GNNQQNY-P21	GNNQQNY-P212121
20.0–2.60	55	13	23	−34	−5
2.60–2.00	27	10	19	−10	−2
2.00–1.70	32	9	15	−36	−10
1.70–1.50	32	26	11	−20	1
1.50–1.35	20	−1	5	−29	4
1.35–1.25	—	15	2	−36	−4
1.25–1.15	—	7	1	−15	−7
1.15–1.10	—	6	−12	−14	−11

The low correlation values indicate that there is no significant anomalous signal from any of the crystals. X-ray data for Zn²⁺-NNQQNY originates from Nelson et al. (27). Data not measured are indicated by a dash.