Peptidoglicano: Diferenzas entre revisións

Algunhas [[Archaea]] teñen unha capa bastante similar pero de [[pseudopeptidoglicano]] ou [[pseudomureína]], na que os residuos de azucres están unidos por enlaces glicosídicos β-(1,3) e os azucres que a forman son a ''N''-acetilglicosamina e a [[ácido N-acetiltalosaminurónico|ácido ''N''-acetiltalosaminurónico]]. Isto explica que a parede das qrqueas sexa insensible á [[lisocima]], que ataca ao peptidoglicano. <ref>Madigan, M. T., J. M. Martinko, P. V. Dunlap, and D. P. Clark. Brock biology of microorganisms. 12th ed. San Francisco, CA: Pearson/Benjamin Cummings, 2009.</ref>

 

 

The peptidoglycan layer is substantially thicker in [[Gram-positive]] [[bacteria]] (20 to 80 nanometers) than in [[Gram-negative]] bacteria (7 to 8 nanometers), with the attachment of the [[S-layer]]. Peptidoglycan forms around 90% of the [[dry weight]] of Gram-positive bacteria but only 10% of Gram-negative strains. Thus, presence of high levels of peptidoglycan is the primary determinant of the characterisation of bacteria as gram-positive.<ref>C.Michael Hogan. 2010. [http://www.eoearth.org/article/Bacteria?topic=49480 ''Bacteria''. Encyclopedia of Earth. eds. Sidney Draggan and C.J.Cleveland, National Council for Science and the Environment, Washington DC]</ref> In Gram-positive strains, it is important in attachment roles and stereotyping purposes.<ref name=Salton1996>{{cite book | author = Salton MRJ, Kim KS | title = Structure. ''In:'' Baron's Medical Microbiology ''(Barron S ''et al.'', eds.)| edition = 4th | publisher = Univ of Texas Medical Branch | year = 1996 | url = http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mmed.section.289#297 | isbn=0-9631172-1-1 }}</ref> For both Gram-positive and Gram-negative bacteria, particles of approximately 2&nbsp;nm can pass through the peptidoglycan.<ref>{{cite journal | author=Demchick PH, Koch AL | title=The permeability of the wall fabric of Escherichia coli and Bacillus subtilis | journal=Journal of Bacteriology | date=1 February 1996| pages=768–73| volume=178 | issue=3 |url=http://jb.asm.org/cgi/reprint/178/3/768 | pmid=8550511 | pmc=177723 }}</ref>