Chemistry of bleomycin. XXIII. Natural abundance 15N-NMR spectroscopic evidence for the structure of bleomycin.

Posttranslational modifications in microcin B17 define an additional class of DNA gyrase inhibitor.

“…In addition, the aromatic/olefmnic proton resonances in MccBl7 ( Fig. 2A), as well as the unusual "3C and '5N resonances, are consistent with the corresponding resonances in known thiazole rings (15)(16)(17). Similar structural analyses of MccBl7, arriving at the same conclusions, were performed independently by Bayer et al (18).…”

Identification of the Internal Axial Ligand of HO2−Cobalt(III)−Bleomycin: 1H{15N} HSQC NMR Investigation of Bleomycin, Deglycobleomycin, and Their Hydroperoxide−Cobalt(III) Complexes

“…The crosspeaks of A-NH 2 and A-NH remain missing. However, an early 1D 15 N NMR study of Blm A 2 in CH 3 OH displayed all of the 17 nitrogen peaks (31). Except for the very high field peaks from nonprotonated nitrogens of bithiazole, pyrimidine, and imidazole rings, which cannot be detected by HSQC experiment, the 15 N chemical shifts in this report are very well correlated with those in 1D 15 N NMR experiments (Table 1s).…”

Structures and energies of lithium amide dimers and trimers: an ab initio study

“…This allows the nitrogen lone-pair p orbitals to lie in the ring planes and to interact with the lithium atoms (compare Figures 1 and 3 with Figures 2 and 4). To probe the effect of such lone-pair orientations, we calculated fully planar arrangements of the dimer and trimer by imposing )2 (8) and D3h (9) symmetries. The geometries of 8 and 9 (Table III) show a decrease (0.04-0.05 A) in the N-Li bond lengths and widening in the NLiN bond angles relative to 4 and 5.…”