lysozyme
Identifiers
Symbol	LYZ
Entrez	4069
HUGO	6740
OMIM	153450
RefSeq	NM_000239
UniProt	P61626
Other data
EC number	3.2.1.17
Locus	Chr. 12 [1]

Lysozyme single crystal.

Lysozyme is a 14.4 kilodalton enzyme (EC 3.2.1.17) that destroys bacterial cell walls by hydrolyzing the polysaccharide component of the cell wall.^[1] It is abundantly present in a number of secretions, such as tears. This protein is present in cytoplasmic granules of the polymorphonuclear neutrophils (PMN) and released through the mucosal secretions (such as tears and saliva). They can also be found in high concentration in egg white. Image File history File links Download high resolution version (817x531, 52 KB) Created by uploader from PDB file using SwissPDB viewer. ... The Entrez logo The Entrez Global Query Cross-Database Search System allows access to databases at the National Center for Biotechnology Information (NCBI) website. ... Hugo is a masculine name. ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... The National Center for Biotechnology Information (NCBI) is part of the US National Library of Medicine (NLM), which is a branch of the US National Institutes of Health. ... Swiss-Prot is a curated biological database of protein sequences created in 1986 by Amos Bairoch during his PhD and developed by the Swiss Institute of Bioinformatics and the European Bioinformatics Institute. ... The Enzyme Commission number (EC number) is a numerical classification scheme for enzymes, based on the chemical reactions they catalyze. ... Short and long arms Chromosome. ... Chromosome 12 is one of the 23 pairs of chromosomes in humans. ... Image File history File links Download high resolution version (1280x1024, 161 KB) Single Protein crystal of Lysozyme Photographed by Mathias Klode File links The following pages link to this file: Lysozyme ... Image File history File links Download high resolution version (1280x1024, 161 KB) Single Protein crystal of Lysozyme Photographed by Mathias Klode File links The following pages link to this file: Lysozyme ... The atomic mass unit (amu), unified atomic mass unit (u), or dalton (Da), is a small unit of mass used to express atomic masses and molecular masses. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... The Enzyme Commission number (EC number) is a numerical classification scheme for enzymes, based on the chemical reactions they catalyze. ... Secretion is the process of segregating, elaborating, and releasing chemicals from a cell, or a secreted chemical substance or amount of substance. ... Also see: Tears (song) by X Japan, or Tears (film) by Im Sang-soo. ... Cytoplasm is the viscid, semi-fluid matter contained within the plasma membrane of a cell that helps to hold the cell together. ... Granulocytes are a category of white blood cells, characterised by the fact that all types have differently staining granules in their cytoplasm on light microscopy. ... Mucus is a slippery secretion of the lining of various membranes in the body (mucous membranes). ... Secretion is the process of segregating, elaborating, and releasing chemicals from a cell, or a secreted chemical substance or amount of substance. ... Also see: Tears (song) by X Japan, or Tears (film) by Im Sang-soo. ... Saliva is the watery and usually somewhat frothy substance produced in the mouths of humans and some animals. ...

Physiology

Most of the bacteria affected by lysozyme are not pathogenic. In some cases, lysozyme is a primary reason these organisms do not become pathogenic. Lysozyme can act to some extent as an innate opsonin, or as an actively lytic enzyme.

Lysozyme serves as a non-specific innate opsonin by binding to the bacterial surface, reducing the negative charge and facilitating phagocytosis of the bacterium before opsonins from the acquired immune system arrive at the scene. In other words, lysozyme makes it easier for phagocytic white blood cells to engulf bacteria. An opsonin is any molecule that acts as a binding enhancer for the process of phagocytosis, for example, by coating the negatively-charged molecules on the membrane. ... White Blood Cells is also the name of a White Stripes album. ...

The enzyme functions by attacking peptidoglycans (found in the cells walls of bacteria, especially Gram-positive bacteria) and hydrolyzing the glycosidic bond that connects N-acetyl muramic 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. 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. Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a homogeneous layer outside the plasma membrane of eubacteria. ... Hydrolysis is a chemical reaction or process in which a chemical compound reacts with water. ... N-acetyl muramic acid, or MurNAc, is identical to N-acetyl glucosamine (GlcNAc) except that it possesses an additional group (specifically, a propanoic acid molecule with a hydrogen atom on the middle carbon replaced by an oxygen atom to form an ether linkage) attached to Carbon 3, in place of... N-Acetylglucosamine (N-Acetyl-D-Glucosamine, or GlcNAc, or NAG) is a monosaccharide derivative of glucose. ... Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a homogeneous layer outside the plasma membrane of eubacteria. ...

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. For further detail see the section on glycoside hydrolases. Glycoside hydrolases (also called glycosidases) catalyze the hydrolysis of the glycosidic linkage to generate two smaller sugars. ...

Role in disease

In some forms of hereditary amyloid, the cause is a mutation in the lysozyme gene, which leads to accumulations lysozyme in several tissues.^[2] Amyloids are insoluble fibrous protein aggregations sharing specific structural traits. ... It has been suggested that mutant be merged into this article or section. ... For a non-technical introduction to the topic, see Introduction to Genetics. ... Biological tissue is a collection of interconnected cells that perform a similar function within an organism. ...

History

Alexander Fleming (1881-1955), the discoverer of penicillin, described lysozyme in 1922.^[3] Alexander Fleming Sir Alexander Fleming (6 August 1881 – 11 March 1955) was a Scottish biologist and pharmacologist. ... Penicillin nucleus Penicillin (sometimes abbreviated PCN) refers to a group of β-lactam antibiotics used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms. ... Year 1922 (MCMXXII) was a common year starting on Sunday (link will display full calendar). ...

Its structure was described by David Chilton Phillips (1924-1999) in 1965 when he got the first 2 angstrom (200 pm) resolution image.^[4][5] 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.^[6] Lord David Phillips is considered to be a founding father of the now expanding field of structural biology and was an influential figure in science and government. ... An angstrom, angström, or Ã¥ngström (symbol Ã…) is a unit of length. ... Picometre (American spelling: picometer) is an SI measure of length that is equal to 10−12 of a metre. ... Neuraminidase ribbon diagram An enzyme (in Greek en = in and zyme = blend) is a protein, or protein complex, that catalyzes a chemical reaction and also controls the 3D orientation of the catalyzed substrates. ...

Howard Florey (1898-1968) and Ernst B. Chain (1906-1979) also investigated lysozymes. Although they never made much progress in this field, they developed penicillin, which Fleming had failed to do. Howard Walter Florey, Baron Florey, OM, FRS, (September 24, 1898 – February 21, 1968) was a pharmacologist who shared the Nobel Prize for Physiology or Medicine in 1945 with Ernst Boris Chain and Sir Alexander Fleming for his role in the extraction of penicillin. ... Sir Ernst Boris Chain (June 19, 1906 – August 12, 1979) was a German-born British biochemist, and a 1945 co-recipient of the Nobel Prize for Physiology or Medicine for his work on penicillin. ...

References

The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ...

External link

• The Lysozyme Protein
• Lysozyme structure and related articles