Crystal growth procedures are available as supplementary information . All X-ray diffraction experiments were carried out at the Caltech Molecular Observatory. Crystals were removed from wells and incubated in a cryoprotectant solution consisting of 30% ethylene glycol, 25% PEG 4000, 100 mM lithium nitrate, 10 mM copper sulfate, and 100 mM tris pH 7.0 for several minutes. During this time the large crystals under a 100 K nitrogen cryostream. 1.54 Å X-rays were generated using a Rigaku rotating anode source. Oscillation images were recorded following determination of crystal parameters in a manner to maximize completeness of the data sets. Images were recorded on a Rigaku Raxis IV++ detector operated with CRYSTALCLEAR.
Reflections were integrated and processed using iMOSFLM29 . Data were scaled and merged using SCALA30 (link). Structures were solved by the method of molecular replacement as implemented in program MOLREP12 (link) using the 2.4 Å structure of azurin C112D (PDBID: 1AG0) as a search model. The MOLREP output was then used for model building with ARP/wARP31 (link), with a single coordinate randomization included to alleviate any possible model bias. Maximum likelihood restrained refinement was carried out using program REFMAC512 (link).
Reflections were integrated and processed using iMOSFLM29 . Data were scaled and merged using SCALA30 (link). Structures were solved by the method of molecular replacement as implemented in program MOLREP12 (link) using the 2.4 Å structure of azurin C112D (PDBID: 1AG0) as a search model. The MOLREP output was then used for model building with ARP/wARP31 (link), with a single coordinate randomization included to alleviate any possible model bias. Maximum likelihood restrained refinement was carried out using program REFMAC512 (link).
