Table 1.

Data collection and isomorphous replacement

Derivative	Resolution limit, Å	Total observations	Unique observations	Completeness, %	Rsym, %	Riso, %	Phasing power
Native	3.0	136,953	21,529	91.9	7.0
U	3.2	25,981	16,119	89.5	11.9	18.1	0.31
PT1	3.7	65,464	11,692	98.2	12.0	22.6	1.54
PT2	4.0	53,870	6,293	66.9	13.3	13.8	1.77
PT3	3.4	85,226	14,155	92.8	10.5	17.1	1.16
PT4	2.6	387,925	27,487	90.6	5.7	35.5	0.67
PT5	2.7	358,695	24,543	88.7	6.1	36.2	0.83
PTU	3.5	79,629	11,437	82.4	9.4	24.7	1.54
PB	3.5	78,190	11,336	92.9	11.5	12.8	0.41
PBPT	3.4	94,557	14,129	91.6	8.0	19.6	1.04
OS	2.8	600,108	24,026	91.2	5.3	38.4	1.82
Overall figure of merit (15.0–3.0 Å): 0.73

Heavy-atom derivatives were prepared by soaking the crystals in low-salt buffer containing the heavy atom as follows: U, 0.5 mM uranyl acatate for 2 h; PT1, 5 mM K₂PtCl₄ for 1 d, PT2, 5 mM K₂PtCl₆ for 2 d; PT3, saturated cis-dichlorodipyridine-Pt(II) for 2 d; PT4, 5 mM K₂PtCl₆ for 7 d; PT5, saturated cis-dichlorodipyridine-Pt(II) for 7 d; PTU, PT1 + U; PB, saturated dinitrophenyl-Pb(NO₃)₂ for 7 d; PBPT, PB + PT5; OS, saturated K₂OsO₄ for 7 d. NAT1, PT1, PT2, PT3, PTU, PB and PBPT were collected with a Mar imaging plate and U was collected with a Bruker AXS area detector on a Rigaku rotating anode source. All other data sets were collected with a Mar charge-coupled device at beamline BW6 at DESY, Hamburg.