| X-RAY DIFFRACTION |
5.5 |
281 |
HmdII from Desulfurobacterium thermolithotrophum was reconstituted with the Fe-guanylylpyridinol cofactor from Methanothermobacter marburgensis and co-crystallized with methenyl-tetrahydrofolate using the sitting drop vapor diffusion method under N2/H2 (95%/5%) in red light condition. The reconstituted holoenzyme was mixed with methenyl-H4F+ at the final concentrations of 1.6 mM. Methenyl-tetrahydrofolate was dissolved in 10% DMSO, and the final concentration of DMSO in the protein solution was 1.6%. 0.7 ul of dHmdII at 21 mg/ml (reconstituted with FeGP and methenyl-H4F+) was spotted on a 96-well 2-drop MRC Crystallization Plates (Molecular Dimensions, Suffolk, UK) and 0.7 ul of reservoir solution was mixed. After one month, crystals appeared in 20% PEG 3000 (w/v) and 100 mM Sodium Citrate pH 5.5 (from the kit WIZARD, Jena Bioscience).
The crystals were cryoprotected by a soak of few seconds in 20% PEG 3000 (w/v), 100 mM Tri-Sodium Citrate pH 5.5 and 20% glycerol before a flash freeze in liquid nitrogen |
