Raja Dey

Preliminary X-ray crystallographic analysis of the secreted chorismate mutase from Mycobacterium tuberculosis: a tricky crystallization problem solved

A method is presented that allowed the diffraction limit of crystals of the secreted chorismate mutase from M. tuberculosis to be improved from approximately 3.5 to 1.3 Å. To obtain large well diffracting crystals, it was critical to initiate crystallization at higher precipitant concentration and then transfer the drops to lower precipitant concentrations within 5–15 min.

5-Amino-1-[2-(diethylamino)ethyl]-1H-imidazole-4-carboxamide

Intramolecular hydrogen bonds influence the molecular conformation of the title compound, C 10 H 19 N 5 O, resulting in an extended planar hydrogen-bonded heterocyclic ring structure. The bulky diethylaminoethyl group adopts a butterfly conformation. The stabilization of the crystal structure is supported by an extensive network of intermolecular hydrogen bonds.

5-Amino-1-benzyl-4-cyano-3-methylimidazolium toluene-p-sulfonate

The title compound, C12H13N4+·C7H7O3S−, contains an imidazolium cation and a toluene-p-sulfonate anion in the asymmetric unit. Hydrogen-bonded dimers are formed between the cyano and amino groups of inversion-related imidazolium cations.

21-Acetoxy-17α-4-pregnene-3,20-dione

The synthetic steroid 21-acetoxy-17α-4-pregnene-3,20-dione, C 23H32O4, crystallizes with a single molecule in the asymmetric unit. The molecule contains four fused rings, typical of steroids. The cyclohexene ring A has nearly the conformation of a boat. One saturated six-membered ring, B, is intermediate between chair and half-chair conformations, while the other six-membered ring, C, is essentially a chair. The five-membered ring D tends towards a twist conformation. The ring junction A/B is quasi-trans, whereas the ring junctions B/C and C/D are both trans. The molecule is slightly convex towards the β side.