Structure and function of peptidoglycans

Detailed knowledge of bacterial cell wall peptidoglycan structures has expanded rapidly in the past few years, and very definite patterns have emerged which can be attributed to common biosynthetic pathways, and, more speculatively, to a common structural function. The glycan is β - 1, 4 linked and is therefore a substituted form of chitin, probably retaining its linear conformation. The peptide may be more flexible, and varied in its cross-linking, but all contain a sequence derived from a probable common precursor, UDP- N- acetylmuramy 1-(A)- D - glu -(B)- D -ala- D - ala, when (A) and (B) are amino acids with the carboxy 1 and a-amino groups of a center with L - configuration in the main chain. The conformation of this sequence is discussed.