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Lysozyme
Identifiers
EC number 3.2.1.17
CAS number 9001-63-2
IntEnz IntEnz view
BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures
Gene Ontology AmiGO / EGO
edit
Lysozyme

PDB rendering based on 132l.
Available structures
133l, 134l, 1b5u, 1b5v, 1b5w, 1b5x, 1b5y, 1b5z, 1b7l, 1b7m, 1b7n, 1b7o, 1b7p, 1b7q, 1b7r, 1b7s, 1bb3, 1bb4, 1bb5, 1c43, 1c45, 1c46, 1c7p, 1cj6, 1cj7, 1cj8, 1cj9, 1ckc, 1ckd, 1ckf, 1ckg, 1ckh, 1d6p, 1d6q, 1di3, 1di4, 1di5, 1eq4, 1eq5, 1eqe, 1gay, 1gaz, 1gb0, 1gb2, 1gb3, 1gb5, 1gb6, 1gb7, 1gb8, 1gb9, 1gbo, 1gbw, 1gbx, 1gby, 1gbz, 1gdw, 1gdx, 1ge0, 1ge1, 1ge2, 1ge3, 1ge4, 1gev, 1gez, 1gf0, 1gf3, 1gf4, 1gf5, 1gf6, 1gf7, 1gf8, 1gf9, 1gfa, 1gfe, 1gfg, 1gfh, 1gfj, 1gfk, 1gfr, 1gft, 1gfu, 1gfv, 1hnl, 1i1z, 1i20, 1i22, 1inu, 1ioc, 1ip1, 1ip2, 1ip3, 1ip4, 1ip5, 1ip6, 1ip7, 1iwt, 1iwu, 1iwv, 1iww, 1iwx, 1iwy, 1iwz, 1ix0, 1iy3, 1iy4, 1jka, 1jkb, 1jkc, 1jkd, 1jsf, 1jwr, 1laa, 1lhh, 1lhi, 1lhj, 1lhk, 1lhl, 1lhm, 1lmt, 1loz, 1lyy, 1lz1, 1lz4, 1lz5, 1lz6, 1lzr, 1lzs, 1op9, 1oua, 1oub, 1ouc, 1oud, 1oue, 1ouf, 1oug, 1ouh, 1oui, 1ouj, 1qsw, 1re2, 1rem, 1rex, 1rey, 1rez, 1tay, 1tby, 1tcy, 1tdy, 1ubz, 1w08, 1wqm, 1wqn, 1wqo, 1wqp, 1wqq, 1wqr, 1yam, 1yan, 1yao, 1yap, 1yaq, 207l, 208l, 2bqa, 2bqb, 2bqc, 2bqd, 2bqe, 2bqf, 2bqg, 2bqh, 2bqi, 2bqj, 2bqk, 2bql, 2bqm, 2bqn, 2bqo, 2hea, 2heb, 2hec, 2hed, 2hee, 2hef, 2lhm, 2mea, 2meb, 2mec, 2med, 2mee, 2mef, 2meg, 2meh, 2mei, 2nwd, 3exd, 3lhm
Identifiers
Symbols LYZ;
External IDs OMIM153450 MGI96897 HomoloGene37278 GeneCards: LYZ Gene
EC number 3.2.1.17
RNA expression pattern
PBB GE LYZ 213975 s at tn.png
More reference expression data
Orthologs
Species Human Mouse
Entrez 4069 17105
Ensembl ENSG00000090382 ENSMUSG00000069516
UniProt P61626 Q3TXG2
RefSeq (mRNA) NM_000239 NM_017372
RefSeq (protein) NP_000230 NP_059068
Location (UCSC) Chr 12:
68.03 - 68.03 Mb
Chr 10:
116.68 - 116.69 Mb
PubMed search [1] [2]
Lysozyme single crystal.

Lysozyme, also known as muramidase or N-acetylmuramide glycanhydrolase, are a family of enzymes (EC 3.2.1.17) which damage bacterial cell walls by catalyzing hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in a peptidoglycan and between N-acetyl-D-glucosamine residues in chitodextrins. Lysozyme is abundant in a number of secretions, such as tears, saliva, human milk and mucus. It is also present in cytoplasmic granules of the polymorphonuclear neutrophils (PMN). Large amounts of lysozyme can be found in egg white. C-type lysozymes are closely related to alpha-lactalbumin in sequence and structure making them part of the same family.

In humans, the lysozyme enzyme is encoded by the LYZ gene.[1][2]

Contents

Function

The enzyme functions by attacking peptidoglycans (found in the cell walls of bacteria, especially Gram-positive bacteria) and hydrolyzing the glycosidic bond that connects N-acetylmuramic acid with the fourth carbon atom of N-acetylglucosamine. It does this by binding to the peptidoglycan molecule in the binding site within the prominent cleft between its two domains. This causes the substrate molecule to adopt a strained conformation similar to that of the transition state[citation needed]. According to Phillips-Mechanism, the lysozyme binds to a hexasaccharide. The lysozyme then distorts the 4th sugar in hexasaccharide (the D ring) into a half-chair conformation. In this stressed state the glycosidic bond is easily broken.

The amino acid side chains glutamic acid 35 (Glu35) and aspartate 52 (Asp52) have been found to be critical to the activity of this enzyme. Glu35 acts as a proton donor to the glycosidic bond, cleaving the C-O bond in the substrate, whilst Asp52 acts as a nucleophile to generate a glycosyl enzyme intermediate. The glycosyl enzyme intermediate then reacts with a water molecule, to give the product of hydrolysis and leaving the enzyme unchanged.

Role in disease

Lysozyme is part of the innate immune system. Reduced lysozyme levels have been associated with bronchopulmonary dysplasia in newborns.[3] Children fed infant formula lacking lysozyme in their diet have three times the rate of diarrheal disease.[4] Since lysozyme is a natural form of protection from pathogens like Salmonella, E.coli and Pseudomonas, a deficiency due to infant formula feeding can lead to increased incidence of disease.[citation needed]

Whereas the skin is a protective barrier due to its dryness and acidity, the conjunctiva (membrane covering the eye) is instead protected by secreted enzymes, mainly lysozyme and defensin. However, when these protective barriers fail, conjunctivitis results.

History

Laschtschenko first described lysozyme in 1909.[5]

Alexander Fleming (1881-1955), the discoverer of penicillin, described lysozyme in 1922.[6]

Its structure was described by David Chilton Phillips (1924-1999) in 1965 when he got the first 2 Ångström (200 pm) resolution image.[7][8] This work led Phillips to provide an explanation for how enzymes speed up a chemical reaction in terms of its physical structures. The original mechanism proposed by Phillips was more recently revised.[9]

Howard Florey (1898-1968) and Ernst B. Chain (1906-1979) also investigated lysozymes. Although they never made much progress in this field, they along with Fleming developed penicillin.

See also

References

  1. ^ Yoshimura K, Toibana A, Nakahama K (January 1988). "Human lysozyme: sequencing of a cDNA, and expression and secretion by Saccharomyces cerevisiae". Biochem. Biophys. Res. Commun. 150 (2): 794–801. doi:10.1016/0006-291X(88)90461-5. PMID 2829884. 
  2. ^ Peters CW, Kruse U, Pollwein R, Grzeschik KH, Sippel AE (July 1989). "The human lysozyme gene. Sequence organization and chromosomal localization". Eur. J. Biochem. 182 (3): 507–16. doi:10.1111/j.1432-1033.1989.tb14857.x. PMID 2546758. 
  3. ^ Revenis ME, Kaliner MA (August 1992). "Lactoferrin and lysozyme deficiency in airway secretions: association with the development of bronchopulmonary dysplasia". J. Pediatr. 121 (2): 262–70. PMID 1640295. 
  4. ^ Lönnerdal B (June 2003). "Nutritional and physiologic significance of human milk proteins". Am. J. Clin. Nutr. 77 (6): 1537S–1543S. PMID 12812151. 
  5. ^ Laschtschenko P (1909). "Über die keimtötende und entwicklungshemmende Wirkung Hühnereiweiß" (in German). Z. Hyg. infektKrankh. 64: 419-427. 
  6. ^ Fleming A (1 May 1922). "On a remarkable bacteriolytic element found in tissues and secretions". Proc Roy Soc Ser B 93 (653): 306–317. doi:10.1098/rspb.1922.0023. http://www.jstor.org/pss/80959. 
  7. ^ Blake CC, Koenig DF, Mair GA, North AC, Phillips DC, Sarma VR. (1965). "Structure of hen egg-white lysozyme. A three-dimensional Fourier synthesis at 2 Angstrom resolution". Nature 206 (986): 757–61. doi:10.1038/35090602. PMID 5891407. 
  8. ^ Johnson LN, Phillips DC. (1965). "Structure of some crystalline lysozyme-inhibitor complexes determined by X-ray analysis at 6 Angstrom resolution". Nature 206 (986): 761–3. doi:10.1038/206761a0. PMID 5840126. 
  9. ^ Vocadlo DJ, Davies GJ, Laine R, Withers SG. (2001). "Catalysis by hen egg-white lysozyme proceeds via a covalent intermediate". Nature 412 (6849): 835–8. doi:10.1038/35090602. PMID 11518970. 

External links








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