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LysozymeLysozyme
Introduction to LysozymeIntroduction to Lysozyme
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Lysozyme (muramidase) is an enzyme that can be found in many animal species. The enzyme is located in saliva, tears, mucous, and human milk. Lysozyme is also found in large concentrations in egg whites from hens. Lysozyme is stable in typical conditions [1] and is valued for its antimicrobial properties, thus there is a lot of research and information behind the function and structure of the enzyme[2]. Lysozyme is crucial to our immune system due to its anti-bacterial properties. The enzyme breaks down the cell membranes of bacterial cells. Lysozyme is a single-chain alkaline protein with 129 amino acid residues and four disulfide bonds. It catalyzes the breakdown of β-1,4-glycosidic bonds in the cell membrane of bacterial cells. Lysozyme is also known to have antiviral, antitumor, and anti-inflammatory properties. [3].
Structural highlightsStructural highlights
Lysozyme (PDB code 1REX) is an enzyme with 129 amino acids and four disulfide bridges. The structure of lysozyme has two major motifs, those being alpha helices and beta strands. Lysozyme had a total of four , in pink, and five , in yellow. These two motifs are regularly found in different innate immune system responses. The helices are connected with a loop, with either 2 or 3 beta strands attached to them.[4] human lysozyme falls under the umbrella of c-type lysozyme. it is stabilized with hydrophobic interactions between (Val117, Ala126, and Trp127), hydrogen bonds at (Asn64, Asn78, Ala126, and Val128), with the conformational changes happening at the active site cleft at Tyr81, Val128, and Arg131[5] The N-terminal helix of lysozyme is most effective against gram-positive bacteria, however, the c-terminus helix has been shown to be effective against all strains of bacteria. However, to be effective against gram-negative bacteria, it has to cross the outer membrane by self-promoted uptake, then it attacks the inner membrane.[6]
FunctionFunction
Lysozyme binds to the membrane of bacterial cells and catalyzes the breakdown of those membranes killing the cell. The carbohydrates forming the membranes of the bacteria cells are what keep the cell together and functioning. When lysozyme binds to these membranes it catalyzes the reaction between the membrane and water, breaking the bonds between the carbohydrates and causing the membrane to fall apart. The positive charge of lysozyme is what draws it to the negative charge of the bacterial membrane[7]. While this is an effective method of destroying bacterial cells, many types of bacteria have developed resistance to it. The two main ways bacteria have developed this resistance is a modification of the cell wall to prevent lysozyme binding and the production of NAG deacetylase in bacteria to destroy the lysozyme before it can bind.
Lysozyme serves an important function in the lungs and airways of humans. The exposure of these areas to airborne pathogens means that there must be a high concentration of lysozyme in order to prevent serious respiratory infections[8].
RelevanceRelevance
Lysozyme serves many important roles in biological functions. By catalyzing the destruction of bacteria it helps protect the body. Under normal conditions lysozyme is stable and easier to study than other enzymes. It can be used as a model for the reactions of other similar enzymes.
Lysozyme is also vital in the understanding of the roles of proteins in diseases and how an organism fends off those diseases. It has been used as a model to understand how enzymes catalyze reactions in the body[9].
Types of LysozymeTypes of Lysozyme
There are three main types of lysozyme, C-type, G-type, and I-type. C-type is the most common and is found in all vertebrates and some insect species. G-type is found predominately in select bird species as well as certain mollusks. I-type is found in a large portion of invertebrates[7]. These types vary slightly but their overall function is similar. C-type is used for its antibacterial properties to protect food in commercial settings. The use of these slight variations in the types of lysozyme can help combat antibiotic resistance in medical settings[10]
ReferencesReferences
- ↑ Avanti C, Saluja V, van Streun EL, Frijlink HW, Hinrichs WL. Stability of lysozyme in aqueous extremolyte solutions during heat shock and accelerated thermal conditions. PLoS One. 2014 Jan 23;9(1):e86244. doi: 10.1371/journal.pone.0086244.
- ↑ Nawaz, N. et al. Lysozyme and Its Application as Antibacterial Agent in Food Industry. Molecules, [s. l.], v. 27, n. 19, p. 6305, 2022. DOI 10.3390/molecules27196305. Disponível em: https://search-ebscohost-com.radford.idm.oclc.org/login.aspx?direct=true&AuthType=ip,sso&db=a9h&AN=159674438&site=eds-live&scope=site. Acesso em: 21 out. 2022.
- ↑ LIU, F. et al. The In Vitro Antimicrobial and Antibiofilm Activities of Lysozyme against Gram-Positive Bacteria. Computational & Mathematical Methods in Medicine, [s. l.], p. 1–10, 2022. DOI 10.1155/2022/4559982. Disponível em: https://search-ebscohost-com.radford.idm.oclc.org/login.aspx?direct=true&AuthType=ip,sso&db=a9h&AN=158444932&site=eds-live&scope=site. Acesso em: 21 out. 2022
- ↑ IBRAHIM, H. R.; HAMASAKI, K.; MIYATA, T. Novel peptide motifs from lysozyme suppress pro-inflammatory cytokines in macrophages by antagonizing toll-like receptor and LPS-scavenging action. European Journal of Pharmaceutical Sciences, [s. l.], v. 107, p. 240–248, 2017. DOI 10.1016/j.ejps.2017.07.005. Disponível em: https://search-ebscohost-com.radford.idm.oclc.org/login.aspx?direct=true&AuthType=ip,sso&db=edselp&AN=S0928098717304049&site=eds-live&scope=site. Acesso em: 21 out. 2022.
- ↑ KI HYUN NAM. Crystal Structure of human lysozyme Complexed with N-Acetyl-α-d-glucosamine. Applied Sciences, [s. l.], v. 12, n. 4363, p. 4363, 2022. DOI 10.3390/app12094363. Disponível em: https://search-ebscohost-com.radford.idm.oclc.org/login.aspx?direct=true&AuthType=ip,sso&db=edsdoj&AN=edsdoj.598c8967a4f349399939b77b7453e41b&site=eds-live&scope=site. Acesso em: 21 out. 2022.
- ↑ IBRAHIM, H. R.; THOMAS, U.; PELLEGRINI, A. A helix-loop-helix peptide at the upper lip of the active site cleft of lysozyme confers potent antimicrobial activity with membrane permeabilization action. The Journal of biological chemistry, [s. l.], v. 276, n. 47, p. 43767–43774, 2001. DOI 10.1074/jbc.M106317200. Disponível em: https://search-ebscohost-com.radford.idm.oclc.org/login.aspx?direct=true&AuthType=ip,sso&db=cmedm&AN=11560930&site=eds-live&scope=site. Acesso em: 14 nov. 2022.
- ↑ 7.0 7.1 Nawaz N, Wen S, Wang F, Nawaz S, Raza J, Iftikhar M, Usman M. Lysozyme and Its Application as Antibacterial Agent in Food Industry. Molecules. 2022 Sep 24;27(19). pii: molecules27196305. doi:, 10.3390/molecules27196305. PMID:36234848 doi:http://dx.doi.org/10.3390/molecules27196305
- ↑ Zhang R, Wu L, Eckert T, Burg-Roderfeld M, Rojas-Macias MA, Lütteke T, et al. (January 2017). "Lysozyme's lectin-like characteristics facilitates its immune defense function". Quarterly Reviews of Biophysics. 50: e9.https://doi.org/10.1017%2FS0033583517000075
- ↑ Merlini G, Bellotti V. Lysozyme: A paradigmatic molecule for the investigation of Proteins structure, function and misfolding Clinica Chimica Acta 357 (2005) 168 – 172 https://www.sciencedirect.com/science/article/pii/S0009898105001932
- ↑ Leśnierowski G.; Yang T. Lysozyme and its modified forms: A critical appraisal of selected properties and potential Trends in Food Science & Technology Volume 107, January 2021, Pages 333-342.