Characterization of gadolinium complexes for SAD phasing in macromolecular crystallography: application to CbpF.

ABSTRACT

Seven Gd complexes were used in the preparation of heavy-atom derivatives for solving the structure of choline-binding protein F (CbpF), a 36 kDa surface protein from Streptococcus pneumoniae, by the SAD method. CbpF was used as a model system to analyse the phasing capability of each of the derivatives. Three different aspects have been systematically characterized the efficacy of cocrystallization versus soaking in the binding of the different Gd complexes, their mode of interaction and a comparative study of SAD phasing using synchrotron radiation and using a rotating-anode generator. This study reveals the striking potential of these complexes for SAD phasing using a laboratory source and further reinforces their relevance for high-throughput macromolecular crystallography.