Structural features of vancomycin.

Recent analytical methods have advanced knowledge of the structure of vancomycin from a description of only several molecular fragments to a complete understanding of the intact molecule. The molecular weight is 1,448. The molecule consists of a seven-membered peptide chain that is formed by parts of three phenylglycine systems, two chlorinated tyrosine units, aspartic acid, and N-methylleucine. Two ether bonds and a carbon-carbon bond join the various substituents on the peptide chain into three large rings. A disaccharide, composed of glucose and vancosamine, is also present but is not part of the cyclic structure. Details of the vancomycin structure have been related to hydrogen bonding between the antibiotic and bacterial cell-wall precursors that have a D-alanyl-D-alanine carboxyl terminus; such bonding would provide a molecular basis for the cell-wall mode of action for vancomycin. With one carboxyl, two amino, and three phenolic groups, vancomycin undergoes a variety of ionic interactions in solutions of different pH and composition.