Editing Lysozyme (section)

{{Short description|Antimicrobial enzyme produced by animals}}
{{cs1 config|name-list-style=vanc|display-authors=6}}
{{Distinguish|Lysosome|Lysosomal enzymes|Lysin}}
{{Use dmy dates|date=August 2020}}
{{infobox enzyme
| Name       = Lysozyme
| EC_number  = 3.2.1.17
| CAS_number = 9001-63-2
| GO_code    = 0003796
}}
{{Infobox protein family 
| image = Lysozymecrystals1.png
| caption = Lysozyme crystals stained with [[methylene blue]].
|Name=Glycoside hydrolase, family 22, lysozyme
|InterPro=IPR000974
|PRINTS=PR00137
}}
'''Lysozyme''' ({{EnzExplorer|3.2.1.17}}, '''muramidase, ''N''-acetylmuramide glycanhydrolase'''; systematic name '''peptidoglycan ''N''-acetylmuramoylhydrolase''') is an [[antimicrobial]] enzyme produced by animals that forms part of the [[innate immune system]]. It is a [[glycoside hydrolase]] that catalyzes the following process:

: Hydrolysis of (1→4)-β-linkages between ''N''-acetylmuramic acid and ''N''-acetyl-<small>D</small>-glucosamine residues in a peptidoglycan and between ''N''-acetyl-<small>D</small>-glucosamine residues in chitodextrins

Peptidoglycan is the major component of [[gram-positive bacteria]]l cell wall.<ref name=":0">{{cite book | vauthors = Manchenko GP | title = Handbook of Detection of Enzymes on Electrophoretic Gels |year = 1994 | publisher = CRC Press | location = Boca Raton, Fla. | isbn = 978-0-8493-8935-1 | page = [https://archive.org/details/handbookofdetect0000manc/page/223 223] | chapter-url = https://www.google.com/search?q=Hydrolysis+of+%281-%3E4%29-beta-linkages+between+N-acetylmuramic+acid+and+N-acetyl-D-glucosamine+residues+in+a+peptidoglycan+and+between+N-acetyl-D-glucosamine+residues+in+chitodextrins#tbs=cdr:1%2Ccd_min:1900%2Ccd_max:2006&tbm=bks&q=Hydrolysis+linkages+between+N-acetylmuramic+acid+N-acetyl-D-glucosamine+residues+in+a+peptidoglycan+and+between+N-acetyl-D-glucosamine+residues+in+chitodextrins&* | chapter = Lysozyme | url-access = registration | url = https://archive.org/details/handbookofdetect0000manc/page/223 }}</ref> This hydrolysis in turn compromises the integrity of bacterial cell walls causing [[lysis]] of the bacteria.

Lysozyme is abundant in [[secretion]]s including [[tears]], [[saliva]], [[human milk]], and [[mucus]]. It is also present in [[cytoplasmic]] granules of the [[macrophages]] and the [[polymorphonuclear neutrophil]]s (PMNs). Large amounts of lysozyme can be found in [[egg white]]. C-type lysozymes are closely related to [[alpha-lactalbumin|α-lactalbumin]] in sequence and structure, making them part of the same [[glycoside hydrolase family 22]].<ref>{{cite web| vauthors = Williams S, Vocadlo D |title= Glycoside hydrolase family 22 |url= https://www.cazypedia.org/index.php/Glycoside_Hydrolase_Family_22 |website=Cazypedia|access-date=11 April 2017}}</ref> In humans, the C-type lysozyme enzyme is encoded by the ''LYZ'' gene.<ref name="Yoshimura_1988">{{cite journal | vauthors = Yoshimura K, Toibana A, Nakahama K | title = Human lysozyme: sequencing of a cDNA, and expression and secretion by Saccharomyces cerevisiae | journal = Biochemical and Biophysical Research Communications | volume = 150 | issue = 2 | pages = 794–801 | date = January 1988 | pmid = 2829884 | doi = 10.1016/0006-291X(88)90461-5 }}</ref><ref name="Peters_1989">{{cite journal | vauthors = Peters CW, Kruse U, Pollwein R, Grzeschik KH, Sippel AE | title = The human lysozyme gene. Sequence organization and chromosomal localization | journal = European Journal of Biochemistry | volume = 182 | issue = 3 | pages = 507–516 | date = July 1989 | pmid = 2546758 | doi = 10.1111/j.1432-1033.1989.tb14857.x | doi-access = free }}</ref>

Hen egg white lysozyme is thermally stable, with a [[melting point]] reaching up to 72&nbsp;°C at pH 5.0.<ref>{{cite journal | vauthors = Venkataramani S, Truntzer J, Coleman DR | title = Thermal stability of high concentration lysozyme across varying pH: A Fourier Transform Infrared study | journal = Journal of Pharmacy & Bioallied Sciences | volume = 5 | issue = 2 | pages = 148–153 | date = April 2013 | pmid = 23833521 | pmc = 3697194 | doi = 10.4103/0975-7406.111821 | doi-access = free }}</ref> However, lysozyme in human milk loses activity very quickly at that temperature.<ref>{{cite journal | vauthors = Chandan RC, Shahani KM, Holly RG | title = Lysozyme Content of Human Milk | journal = Nature | volume = 204 | issue = 4953 | pages = 76–77 | date = October 1964 | pmid = 14240122 | doi = 10.1038/204076a0 | s2cid = 4215401 | bibcode = 1964Natur.204...76C }}</ref> Hen egg white lysozyme maintains its activity in a large range of pH (6–9).<ref>{{cite web | url = https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Datasheet/7/l7651dat.pdf | title = Lysozyme, Product information | publisher = Sigma-Aldrich }}</ref> Its [[isoelectric point]] is 11.35.<ref>{{cite web | url = https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Datasheet/7/l7651dat.pdf | title = Lysozyme, Product information | publisher = Sigma-Aldrich }}</ref> The isoelectric point of human milk lysozyme is 10.5–11.<ref>{{cite journal | vauthors = Parry RM, Chandan RC, Shahani KM | title = Isolation and characterization of human milk lysozyme | journal = Archives of Biochemistry and Biophysics | volume = 130 | issue = 1 | pages = 59–65 | date = March 1969 | pmid = 5778672 | doi = 10.1016/0003-9861(69)90009-5 | doi-access = free }}</ref>