Table 2. Ni ion bond lengths, Å.

Bond	Low-dose big cell	Intermediate-dose big cell	High-dose big cell	High-dose small cell	-reduced big cell
Ni—His-1 Nδ	2.63	3.69	3.87	3.96	3.81
Ni—His-1 N	2.11	2.12	2.06	2.07	2.17
Ni—Cys-2 N	1.93	1.94	1.93	1.94	1.99
Ni—Cys-2 Sγ	2.24	2.23	2.22	2.24	2.30
Ni—Cys-6 Sγ	2.26	2.25	2.20	2.18	2.29

Values are the average over the 12 and 6 independent subunits in the asymmetric unit of the big-cell and small-cell crystal forms, respectively.