The structure of the Escherichia coli response regulator NarL has been solved in a new, monoclinic space group, and compared with the earlier orthorhombic crystal structure. Because the monoclinic crystal has two independent NarL molecules per asymmetric unit, we now have three completely independent snapshots of the NarL molecule: two from the monoclinic form and one from the orthorhombic. Com...

The commentary seeks to provide a brief history and perspective on the importance of crystal forms of pharmaceuticals as a means of achieving performance criteria. The expanding scope of crystal form selection, emergence of crystal engineering in pharmaceutical science and pharmaceutical co-crystals are topics of this brief review.

In the title compound, C23H18O4, the meth-oxy-benzene ring and attached C=C grouping are disordered over two sets of sites in a 0.823 (5):0.177 (5) ratio. The dihedral angles between the central benzene ring and the pendant phenyl and meth-oxy-benzene ring (major orientation) are 51.21 (1) and 51.6 (1)°, respectively. In the crystal, inversion dimers linked by pairs of C-H⋯O hydrogen bonds gene...

In the title compound, C24H22Br2N2S, the dihedral angles between the central pyrimidine ring and the pendant bromo-benzene rings are 11.02 (11) and 13.20 (12)°. The butyl side chain adopts a gauche conformation [C-C-C-C = -67.4 (4)°]. In the crystal, weak aromatic π-π stacking is observed between the pyrimidine ring and one of the benzene rings [centroid-centroid separation = 3.6718 (17) Å].

A new crystal form of penicillin acylase (penicillin amidohydrolase, E.C. 3.5.1.11) from Escherichia coli W (ATCC 11105) is reported. The crystals were grown using a combination of hanging-drop and streak-seeding methods. The crystals are in the monoclinic space group P2(1) with cell dimensions a = 51.52, b = 131.95, c = 64.43 A, beta = 106.12 degrees. There is one heterodimer in the asymmetric...

Thiamin pyrophosphokinase (TPK) transfers a pyrophosphate group from ATP to the hydroxyl group of thiamin and produces thiamin pyrophosphate (TPP). TPP is the cofactor of metabolically important enzymes such as pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, branched-chain α-keto acid dehydrogenase, transketolase and 2-hydroxyphytanoyl-CoA lyase. Thiamin deficiency results in Wernike-Kor...

The epitaxial growth of antimonide-based nanowires has become an attractive subject due to their interesting properties required for various applications such as long-wavelength IR detectors. The studies conducted on antimonide-based nanowires indicate that they preferentially crystallize in the zinc blende (ZB) crystal structure rather than wurtzite (WZ), which is common in other III-V nanowir...

Famotidine Form B P. P. Upadhyay, M. K. Mishra, U. Ramamurty, A. D. Bond University of Copenhagen, Indian Institute of Science, University of Cambridge Purpose Polymorphs are well known to have different mechanical properties. Nanoindentation enables mechanical properties to be tested on single crystals, which should provide the best opportunity to establish a correlation with single-crystal X-...

The fundamental question of how sequence defines conformation is explicitly answered if the structures of all possible sequences of a macromolecule are determined. We present here a crystallographic screen of all permutations of the inverted repeat DNA sequence d(CCnnnN6N7N8GG), where N6, N7, and N8 are any of the four naturally occurring nucleotides. At this point, 63 of the 64 possible permut...