| 词条 | Xanthan lyase |
| 释义 |
| Name = xanthan lyase | EC_number = 4.2.2.12 | CAS_number = 113573-69-6 | IUBMB_EC_number = 4/2/2/12 | GO_code = 0047492 | image = | width = | caption = }} In enzymology, a xanthan lyase ({{EC number|4.2.2.12}}) is an enzyme that catalyzes the chemical reaction of cleaving the beta-D-mannosyl-beta-D-1,4-glucuronosyl bond on the polysaccharide xanthan. This enzyme belongs to the family of lyases, specifically those carbon-oxygen lyases acting on polysaccharides. Xanthan lyase was first identified and partially purified in 1987.[1] Xanthan is a polysaccharide secreted by several different bacterial taxa, such as the plant pathogen Xanthomonas campestris, and it consists of a main linear chain based on cellulose with side chains attached to alternate glucosyl (glucose) residues.[2] These side chains contain three monosaccharide residues. Xanthan lyase is produced by bacteria that degrade this polysaccharide, such as Bacillus, Corynebacterium and Paenibacillus species.[2][3] Industrial applicationsXanthan is used in industry as a thickening agent in foods and drinks, as a stabilizing agent for foams, as a means of enhancing oil recovery and in the manufacture of good such as paints, cosmetics and explosives.[3] The use of xanthan lyase as a means of altering the physical properties of xanthans is an area of current research in biotechnology. Structural studiesAs of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes {{PDB link|1J0M}}, {{PDB link|1J0N}}, {{PDB link|1X1H}}, {{PDB link|1X1I}}, {{PDB link|1X1J}}, {{PDB link|2E22}}, and {{PDB link|2E24}}. The enzyme from Bacillus is a monomer consisting of two domains: an alpha helical N-terminal domain, and a C-terminal domain composed of beta sheets.[4] The active site is a deep cleft located between these two domains. References1. ^{{cite journal |author=Sutherland IW |title=Xanthan lyases--novel enzymes found in various bacterial species |journal=J. Gen. Microbiol. |volume=133 |issue=11 |pages=3129–34 |year=1987 |pmid=3446747 |doi=10.1099/00221287-133-11-3129}} 2. ^1 {{cite journal |vauthors=Hashimoto W, Miki H, Tsuchiya N, Nankai H, Murata K |title=Xanthan lyase of Bacillus sp. strain GL1 liberates pyruvylated mannose from xanthan side chains |journal=Appl. Environ. Microbiol. |volume=64 |issue=10 |pages=3765–8 |date=1 October 1998|pmid=9758797 |pmc=106543 }} 3. ^1 {{cite journal |vauthors=Ruijssenaars HJ, de Bont JA, Hartmans S |title=A pyruvated mannose-specific xanthan lyase involved in xanthan degradation by Paenibacillus alginolyticus XL-1 |journal=Appl. Environ. Microbiol. |volume=65 |issue=6 |pages=2446–52 |date=1 June 1999|pmid=10347025 |pmc=91360 }} 4. ^{{cite journal |vauthors=Hashimoto W, Nankai H, Mikami B, Murata K |title=Crystal structure of Bacillus sp. GL1 xanthan lyase, which acts on the side chains of xanthan |journal=J. Biol. Chem. |volume=278 |issue=9 |pages=7663–73 |year=2003 |pmid=12475987 |url=http://www.jbc.org/cgi/content/full/278/9/7663 |doi=10.1074/jbc.M208100200}}
2 : EC 4.2.2|Enzymes of known structure |
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