The
enzyme xanthan lyase ()
catalyzes
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
the following process:
:Eliminative cleavage of the terminal β-
D-mannosyl-(1→4)-β-
D-glucuronosyl linkage of the side-chain of the polysaccharide xanthan, leaving a 4-deoxy-α-
L-''threo''-hex-4-enuronosyl group at the terminus of the side-chain
It belongs to the family of
lyase
In biochemistry, a lyase is an enzyme that catalyzes the breaking (an elimination reaction) of various chemical bonds by means other than hydrolysis (a substitution reaction) and oxidation, often forming a new double bond or a new ring structure. ...
s, specifically those carbon-oxygen lyases acting on polysaccharides. Xanthan lyase was first identified and partially purified in 1987.
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.
These side chains contain three monosaccharide residues. Xanthan lyase is produced by bacteria that degrade this polysaccharide, such as ''
Bacillus'', ''
Corynebacterium
''Corynebacterium'' () is a genus of Gram-positive bacteria and most are aerobe, aerobic. They are bacillus (shape), bacilli (rod-shaped), and in some phases of life they are, more specifically, club (weapon), club-shaped, which inspired the gen ...
'', ''
Bacteroides'', ''
Ruminococcaceae'', and ''
Paenibacillus'' species.
Industrial applications
Xanthan 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.[ The use of xanthan lyase as a means of altering the physical properties of xanthans is an area of current research in biotechnology.
]
Structural studies
As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes , , , , , , and . 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 sheet
The beta sheet, (β-sheet) (also β-pleated sheet) is a common motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone hydrogen bonds, forming a g ...
s.
References
*
EC 4.2.2
Enzymes of known structure
{{4.2-enzyme-stub