Three-dimensional molecular models of bacterial cell wall mucopeptides (peptidoglycans)

Molecular models have been built of mucopeptides (peptidoglycans) from various species of bacteria. If pairs of glycan chains are hydrogen-bonded as are those of chitin, the carboxyl groups of muramic acid are so oriented that a regular three-dimensional structure can be built. Helical conformation of the peptides is not likely, but pseudo-beta conformation gives the possibility of multiple interpeptide hydrogen bonding. Calculations of the expected dimensions of the cell wall from the model for mucopeptide give results of the right order for bacilli. The effect of the configuration of the amino acids on the conformation of the peptide has been examined.