Download MendeleyStructure-activity relationship of 6-methylidene penems bearing tricyclic heterocycles as broad-spectrum beta-lactamase inhibitors: crystallographic structures show unexpected binding of 1,4-thiazepine intermediates
Venkatesan, A.M., Gu, Y., Dos Santos, O., Abe, T., Agarwal, A., Yang, Y., Petersen, P.J., Weiss, W.J., Mansour, T.S., Nukaga, M., Hujer, A., Bonomo, R.A., Knox, J.R.(2004) J Med Chem 47: 6556-6568
- PubMed: 15588091
- DOI: https://doi.org/10.1021/jm049680x
- Primary Citation of Related Structures:
1Q2P, 1Q2Q - PubMed Abstract:
The design and synthesis of a series of seven tricyclic 6-methylidene penems as novel class A and C serine beta-lactamase inhibitors is described. These compounds proved to be very potent inhibitors of the TEM-1 and AmpC beta-lactamases and less so against the class B metallo-beta-lactamase CcrA. In combination with piperacillin, their in vitro activities enhanced susceptibility of all class C resistant strains from various bacteria. Crystallographic structures of a serine-bound reaction intermediate of 17 with the class A SHV-1 and class C GC1 enzymes have been established to resolutions of 2.0 and 1.4 A, respectively, and refined to R-factors equal 0.163 and 0.145. In both beta-lactamases, a seven-membered 1,4-thiazepine ring has formed. The stereogenic C7 atom in the ring has the R configuration in the SHV-1 intermediate and has both R and S configurations in the GC1 intermediate. Hydrophobic stacking interactions between the tricyclic C7 substituent and a tyrosine side chain, rather than electrostatic or hydrogen bonding by the C3 carboxylic acid group, dominate in both complexes. The formation of the 1,4- thiazepine ring structures is proposed based on a 7-endo-trig cyclization.
Organizational Affiliation:
Wyeth Research, 401 N. Middletown Road, Pearl River, New York 10965, USA.
