@article{mbs:/content/journal/micro/10.1099/00221287-99-1-171, author = "Weston, A. and Ward, J.B. and Perkins, H.R.", title = "Biosynthesis of Peptidoglycan in Wall plus Membrane Preparations from Micrococcus luteus: Direction of Chain Extension, Length of Chains and Effect of Penicillin on Cross-linking", journal= "Microbiology", year = "1977", volume = "99", number = "1", pages = "171-181", doi = "https://doi.org/10.1099/00221287-99-1-171", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-99-1-171", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "SUMMARY: A wall + membrane preparation from Micrococcus luteus was used to synthesize radioactively labelled peptidoglycan. The newly synthesized peptidoglycan either was cross-linked by transpeptidation to existing wall or remained associated with the membrane fraction but was not cross-linked. The average biosynthetic chain lengths, calculated from the ratio of free reducing groups of muramic acid to total muramic acid, were 66 disaccharide units for cross-linked and 26 disaccharide units for the uncross-linked material. The latter value was confirmed by the release of lactyl peptide side chains by β-elimination. Benzylpenicillin (1 µg ml−1) inhibited cross-linking but not overall synthesis of glycan whereas at concentrations above 10 µg ml−1 overall glycan synthesis was slightly inhibited. In the presence of 100 µ;g benzylpenicillin ml−1 the incorporation of disaccharide units to existing walls decreased to 25% of the control. This residual incorporation represented extension by transglycosylation of peptidoglycan already cross-linked to existing walls. Chains with an average length of between 30 and 45 disaccharide units were added during a 30 min incubation period. However, if incubation was continued for up to 120 min (in the presence of 100 µg benzylpenicillin ml−1) a considerable amount of the newly synthesized peptidoglycan was lost from the purified wall because autolytic enzymes were expressed in the wall + membrane preparation after the action of the antibiotic.", }