during purification, haemophilus haemolyticus methyltransferase was overexpressed and purified using a high salt back-extraction step to selectively solubilize m.hhai, followed by fast protein liquid chromatography (fplc) as done previously by kumar and colleagues. authors utilized a mono-q anion exchange column to remove the small quantity of proteinaceous materials and unwanted dna prior to the crystallization step. once m.hhai was successfully purified, the sample was then grown using a method that mixes the solution containing the complex at a temperature of 16 °c and the hanging-drop vapor diffusion technique to obtain the crystals. authors were then able to collect the x-ray data according to a technique used by cheng and colleagues in 1993. this technique involved the measurement of the diffraction intensities on a fast detector, where the exposure times for 0.1° rotation were 5 or 10 seconds. for the structure determination and refinement, klimasaukas and colleagues used the molecular replacement of the refined apo structure described by cheng and colleagues in 1993 where the search models x-plor, merlot, and trnsum were used to solve the rotation and translation functions. this part of the study involves the use of a variety of software and computer algorithms to solve the structures and characteristics of the crystal of interest.