Conformational analysis of bacitracin A, a naturally occurring lariat

Abstract

The proton nmr spectra of bacitracin A in H2O and DMSO-d6 have been assigned and the conformational behavior of the peptide in the two solvents has been compared. Although bacitracin A shows a conformational equilibrium between at least two conformations differing in the relative position of the cyclic and linear domains of the molecule, the spectra in water can be interpreted in terms of a preferred conformation in which the linear part is folded over the cyclic moiety and a turn is present around Ile(8)-DPhe(9).

Proton NMR Studies of Co(II) Complexes of the Peptide Antibiotic Bacitracin and Analogues: Insight into Structure−Activity Relationship

“…The 1 H NMR spectrum of bacitracin A 1 is essentially identical to that previously reported at pH 3.2 and pH 5.15 (22).…”

“…The mass spectra show that the isolated bacitracin A 1 ([M + H] + , m/z 1422.8) and bacitracins B 1 and B 2 ([M + H] + , m/z 1408.6) have the appropriate parent ion peaks similar to previous observations (7). The 1 H NMR spectrum of bacitracin A 1 is essentially identical to that previously reported at pH 3.2 and pH 5.15 (22).…”

High-resolution crystal structure reveals molecular details of target recognition by bacitracin

“…Structures have been determined for metal-free bacitracin alone in solution (22,23) and in complex with several different proteases (24,25). Notably, the antibiotic adopts a broad range of conformations in these structures, indicating that the molecule possesses considerable intrinsic flexibility.…”