Editing Peptidoglycan (section)

== Inhibition and degradation ==
Some [[Antibiotics|antibacterial drugs]] such as [[penicillin]] interfere with the production of peptidoglycan by binding to bacterial enzymes known as [[penicillin-binding proteins]] or [[DD-Transpeptidase|<small>DD</small>-transpeptidase]]s.<ref name="Salton-1996" /> Penicillin-binding proteins form the bonds between oligopeptide crosslinks in peptidoglycan. For a bacterial cell to reproduce through [[binary fission]], more than a million peptidoglycan subunits (NAM-NAG+oligopeptide) must be attached to existing subunits.<ref>{{cite book |author=Bauman R |title=Microbiology with Diseases by Taxonomy |publisher=Benjamin Cummings |year=2007 |isbn=978-0-8053-7679-1 |edition=2nd}}</ref> Mutations in genes coding for transpeptidases that lead to reduced interactions with an antibiotic are a significant source of emerging [[antibiotic resistance]].<ref>{{cite journal | vauthors = Spratt BG | title = Resistance to antibiotics mediated by target alterations | journal = Science | volume = 264 | issue = 5157 | pages = 388–393 | date = April 1994 | pmid = 8153626 | doi = 10.1126/science.8153626 | bibcode = 1994Sci...264..388S | s2cid = 30578841 }}</ref> Since peptidoglycan is also lacking in L-form bacteria and in mycoplasmas, both are resistant against penicillin.

Other steps of peptidoglycan synthesis can also be targeted. The topical antibiotic [[bacitracin]] targets the utilization of [[C55-isoprenyl pyrophosphate]]. [[Lantibiotics]], which includes the food preservative [[nisin]], attack lipid II.<ref>{{cite journal | vauthors = Sarkar P, Yarlagadda V, Ghosh C, Haldar J | title = A review on cell wall synthesis inhibitors with an emphasis on glycopeptide antibiotics | journal = MedChemComm | volume = 8 | issue = 3 | pages = 516–533 | date = March 2017 | pmid = 30108769 | pmc = 6072328 | doi = 10.1039/c6md00585c }}</ref>

[[Lysozyme]], which is found in tears and constitutes part of the body's [[innate immune system]] exerts its antibacterial effect by breaking the β-(1,4)-glycosidic bonds in peptidoglycan (see above). Lysozyme is more effective in acting against [[gram-positive bacteria]], in which the peptidoglycan cell wall is exposed, than against [[gram-negative bacteria]], which have an outer layer of [[Lipopolysaccharide|LPS]] covering the peptidoglycan layer.<ref name="Murphy-2017" /> Several bacterial peptidoglycan modifications can result in resistance to degradation by lysozyme. Susceptibility of bacteria to degradation is also considerably affected by exposure to [[antibiotic]]s. Exposed bacteria synthesize peptidoglycan that contains shorter sugar chains that are poorly crosslinked and this peptidoglycan is then more easily degraded by lysozyme.<ref name="Sun-2022" />