Affiliation: | (1) Department of Chemistry, The University of York, Heslington York YO10 5DD, UK e-mail: akd1@york.ac.uk, GB;(2) EMBL Outstation Hamburg, c/o DESY, Notkestrasse 85 D-22603 Hamburg, Germany, DE;(3) Nitrogen Fixation Laboratory, John Innes Centre, Colney Lane Norwich NR4 7UH, UK, GB |