title: Epimerization and stereochemistry of avoparcin.
abstract: The epimerization of avoparcin entities is discussed in some detail. The absolute stereochemistry of avoparcin is now known since the N-methyl terminal amino acid of the aglycone has been isolated and shown to exhibit negative optical rotation and hence has the R-configuration. The same amino acid has been isolated from an epimerized solution of avoparcin and found to have positive rotation and hence the S-configuration. A comparison is made of the CD curves of beta-avoparcin and epi-beta-avoparcin. Some discussion on the effect of protonation of the terminal N-methyl group on the antibacterial activity of avoparcin is included.
mesh_terms: D000900:Anti-Bacterial Agents; D001419:Bacteria / Q000187:drug effects; D055598:Chemical Phenomena; D002621:Chemistry; D004355:Drug Stability; D006020:Glycopeptides / Q000633:toxicity; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests; D013237:Stereoisomerism
chemical_list: D000900:Anti-Bacterial Agents; D006020:Glycopeptides; C016249:avoparcin