Peptidoglycan: Difference between revisions
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Peptidoglycan is found in both Gram-negative and Gram-positive bacteria. It is present in larger amounts in Gram-positive bacteria as it appears as a multimolecular layer and can be found in association with additional compounds. In Gram-negative bacteria, it is | Peptidoglycan is found in both [[Gram-negative|Gram-negative]] and [[Gram-positive|Gram-positive]] [[Bacteria|bacteria]]. It is present in larger amounts in Gram-positive bacteria as it appears as a multimolecular layer and can be found in association with additional compounds. In Gram-negative bacteria, it is found in either 1 or 2 layers between the inner and outer membrane<ref>http://www.chem.qmul.ac.uk/iupac/misc/glycp.html#3.9</ref>. | ||
Peptidoglycan is a | Peptidoglycan is a [[Macromolecule|macromolecule]] made up of alternating [[Residues|residues]] of [[N-acetyl-β-D-glucosamine|N-acetyl-β-D-glucosamine]] (NAG) and [[N-acetylmuramic acid|N-acetylmuramic acid]] (NAM) joined together by a [[Glycosidic bond|glycosidic bond]]<ref>http://faculty.ccbcmd.edu/courses/bio141/lecguide/unit1/prostruct/cw.html</ref>. There is then a [[Pentapeptide|pentapeptide]] attached to the NAM amino acid which forms cross-links with other polysaccharide chains forming a 3D mesh-like layer. These cross-links are formed using the enzyme [[Glycopeptide transpeptidase|glycopeptide transpeptidase]] and provide peptidoglycan with stability. This stability allows it to provide mechanical support and prevent osmotic lysis from occurring in bacteria<ref>Berg J., Tymoczko J and Stryer L. (2012) Biochemistry, 7th edition, New York: WH Freeman: pg 252</ref>. | ||
Penicillin [[Inhibits]] the effect of peptidoglycan in | [[Penicillin|Penicillin]] [[Inhibits|inhibits]] the effect of peptidoglycan in bacteria by binding to [[Serine|serine]] in the enzyme [[Glycopeptide transpeptidase|glycopeptide transpeptidase]]. As a result, it can no longer catalyse the formation of cross-links. The enzyme is irreversibly inhibited which therefore results in the termination of bacterial growth<ref>http://www.ncbi.nlm.nih.gov/books/NBK7986/</ref>. | ||
Penicillin inhibits the transpeptidase linking together the polysaccharide chains and cells become osmotically sensitive and burst. | |||
=== References === | |||
<references /> | <references /> | ||
Latest revision as of 16:22, 17 October 2018
Peptidoglycan is found in both Gram-negative and Gram-positive bacteria. It is present in larger amounts in Gram-positive bacteria as it appears as a multimolecular layer and can be found in association with additional compounds. In Gram-negative bacteria, it is found in either 1 or 2 layers between the inner and outer membrane[1].
Peptidoglycan is a macromolecule made up of alternating residues of N-acetyl-β-D-glucosamine (NAG) and N-acetylmuramic acid (NAM) joined together by a glycosidic bond[2]. There is then a pentapeptide attached to the NAM amino acid which forms cross-links with other polysaccharide chains forming a 3D mesh-like layer. These cross-links are formed using the enzyme glycopeptide transpeptidase and provide peptidoglycan with stability. This stability allows it to provide mechanical support and prevent osmotic lysis from occurring in bacteria[3].
Penicillin inhibits the effect of peptidoglycan in bacteria by binding to serine in the enzyme glycopeptide transpeptidase. As a result, it can no longer catalyse the formation of cross-links. The enzyme is irreversibly inhibited which therefore results in the termination of bacterial growth[4].
Penicillin inhibits the transpeptidase linking together the polysaccharide chains and cells become osmotically sensitive and burst.
References
- ↑ http://www.chem.qmul.ac.uk/iupac/misc/glycp.html#3.9
- ↑ http://faculty.ccbcmd.edu/courses/bio141/lecguide/unit1/prostruct/cw.html
- ↑ Berg J., Tymoczko J and Stryer L. (2012) Biochemistry, 7th edition, New York: WH Freeman: pg 252
- ↑ http://www.ncbi.nlm.nih.gov/books/NBK7986/