Reductive methylation to improve crystallization of the putative oxidoreductase Rv0765c from Mycobacterium tuberculosis

Rv0765c from Mycobacterium tuberculosis was cloned and heterologously expressed in Escherichia coli . It was purified using affinity and size‐exclusion chromatographic techniques and crystallized. The native protein crystallized in a hexagonal crystal form which diffracted to 7 Å resolution. In an attempt to improve the quality of the Rv0765c crystals, the protein was modified by reductive methylation using dimethylaminoborane and formaldehyde. The modified protein crystallized under different conditions in a tetragonal crystal form, from which diffraction data could be collected to a resolution of 3.2 Å. In both crystal forms of Rv0765c, the asymmetric unit contained two copies of the protein molecule.