Efficient allelic exchange mutagenesis in group B streptococci (GBS) has been hampered by the lack of a counterselectable marker system. Growth inhibition of GBS by the glutamine analog gamma-glutamyl hydrazide requires glnQ. We have used this phenomenon to create a counterselectable marker system for efficient selection of allelic exchange mutants in GBS.

In the structure of the title compound, C(7)H(7)IN(2)O, the hydrazide group is inclined at 13.3 (3)° with respect to the benzene ring. The structure is stabilized by inter-molecular N-H⋯N and N-H⋯O hydrogen bonds involving the hydrazide group, resulting in six- and ten-membered rings with R(2) (2)(6) and R(2) (2)(10) graph-set notations, respectively.

In the title Schiff base compound, C(19)H(16)N(2)O(3), the dihedral angle between the mean planes of the benzene ring and the naphthyl ring system is 0.8 (2)°. The mean plane of the hydrazide group forms dihedral angles of 2.0 (2) and 2.2 (2)°, respectively, with the mean planes of the benzene ring and the naphthyl ring system. A strong intra-molecular N-H⋯O hydrogen bond is present. In the cry...

Substitution of the amide donors in open-chain {2N(oxime), 2N(amide)} ligands by hydrazide donors gives new pseudo-macrocyclic copper complexes that show a significant decrease of the Cu(3+/2+) redox potentials in both mono- and polynuclear systems, thus demonstrating a pronounced capacity of such ligand systems to efficiently stabilize the trivalent copper.

In the title compound, C(12)H(11)N(3)O(2)S, the pyridine ring is inclined to the thio-phene ring, forming a dihedral angle of 34.96 (7)°. The mean plane through the hydrazide unit forms dihedral angles of 21.57 (8) and 53.08 (8)°, respectively, with the pyridine and thio-phene rings. The two O atoms are twisted away from each other, as indicated by the C-N-N-C torsion angle of -81.27 (15)°. In ...

The asymmetric unit of the the title compound, C(7)H(7)ClN(2)O, contains two mol-ecules in which the chloro-phenyl and the formic hydrazide units are almost planar (r.m.s. deviations of 0.0081 and 0.0100 Å, respectively, in one mol-ecule and 0.0069 and 0.0150 Å in the other) and are oriented with respect to each other at dihedral angles of 56.8 (2) and 56.9 (2)°. In the crystal, the mol-ecules ...