Table 1

Data statistics of the crystallographic analysis. A high-resolution native data set, four-wavelength MAD experiment on a SeMet crystal and a single data set on an iridium derivative were collected on beamline X4A of the NSLS with a Quantum 4R charge-coupled device detector. Data were integrated and merged using the HKL software suite (33). Difference Fourier maps that were made with phasing from the iridium derivative and calculated with MLPHARE (40) were used to find the five selenium sites in the SeMet crystal. Numbers in parentheses refer to the highest resolution shell (3.11 to 3.00 Å for SeMet λ1, λ2, λ3, and λ4 and K2IrCl6, and 1.97 to 1.90 Å for the native crystal). The residual data errorR sym = Σ|I − 〈I〉|/ΣI, where I is observed intensity and 〈I〉 is average intensity. Unique reflections for nonnative data consider Bijvoet mates to be inequivalent.

CrystalWave- length λ (Å)Resolution range (Å)ReflectionsData statistics〈/〉/〈σIMulti- plicityNum- ber of sites
UniqueMeasuredCoverage (%)Rsym
Native0.9537020.0–1.921,512569,51698.0 (93.3)0.044 (0.143)30.244.4
SeMet λ10.9871020.0–3.010,242106,41099.3 (100.0)0.046 (0.145)38.924.25
SeMet λ20.9792020.0–3.010,214103,00499.2 (100.0)0.043 (0.125)44.024.25
SeMet λ30.9788020.0–3.010,11096,87598.9 (100.0)0.046 (0.098)34.834.25
SeMet λ40.9641120.0–3.010,15599,56199.5 (100.0)0.042 (0.087)42.554.25
K2IrCl4 0.9536920.0–3.010,469144,24297.2 (99.4)0.076 (0.121)23.705.42