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Aminoacyl-tRNA synthetases are essential enzymes that transmit information from the genetic code to proteins in cells and are targets for antipathogen drug development. Elucidation of the crystal structure of cytoplasmic lysyl-tRNA synthetase from the malaria parasite Plasmodium falciparum (PfLysRS) has allowed direct comparison with human LysRS. The authors' data suggest that PfLysRS is dimeric in solution, whereas the human counterpart can also adopt tetrameric forms. It is shown for the first time that PfLysRS is capable of synthesizing the signalling molecule Ap4a (diadenosine tetraphosphate) using ATP as a substrate. The PfLysRS crystal structure is in the apo form, such that binding to ATP will require rotameric changes in four conserved residues. Differences in the active-site regions of parasite and human LysRSs suggest the possibility of exploiting PfLysRS for selective inhibition. These investigations on PfLysRS further validate malarial LysRSs as attractive antimalarial targets and provide new structural space for the development of inhibitors that target pathogen LysRSs selectively.

The preparation of a series of substituted biphenylferrocenes via a modified Suzuki reaction between 4-bromophenylferrocene and substituted phenylboronic acids is described. The X-ray crystal structure of 4′-formyl-4-biphenylferrocene is reported and this compound is then incorporated into the first series of ferrocenomesogens containing the ferrocenylbiphenyl unit. The synthesis of a series of arylferrocenylphenyl ethers and arylferrocenylphenyl amines is also described.

In the title compound, C(15)H(16)N(2)O(2)S, the N-C(=S) bond lengths are indicative of the presence of amide-type resonance. The dihedral angles between the thio-urea unit and the attached aromatic rings are 59.80 (5) and 73.41 (4)° while the dihedral angle between the rings is 56.83 (4)°. In the crystal, inversion dimers linked by pairs of N-H⋯S hydrogen bonds occur. An N-H⋯π inter-action is observed for the second amino group. The shortest centroid-centroid distance between two aromatic systems is 4.0958 (8) Å.