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Difference between revisions of "Polysaccharide Lyases"
Harry Brumer (talk | contribs) (Added some references.) |
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== Introduction == | == Introduction == | ||
| − | Polysaccharide lyases (PLs) cleave uronic acid-containing polysaccharides via a β-elimination mechanism to generate an unsaturated hexenuronic acid residue and a new reducing end at the point of cleavage <cite>Lombard2010 Garron2010</cite>. PLs have been grouped into families and subfamilies within the Carbohydrate-Active Enzyme (CAZy) framework and that the PLs included are restricted to those operating via ''syn''- and ''anti''-elimination mechanisms <cite>Lombard2010</cite>. In this way, they are distinct from carbon-oxygen lyases that modify polysaccharide composition. Broadly, the mechanism of PL action can be described as consisting of three events: (i) abstraction of the C-5 proton on the sugar ring of a uronic acid or ester by a charge stabilizing cation such as Ca<sup>2+</sup> or a basic amino acid side chain, (ii) stabilization of the resulting anion by charge delocalization onto the C-6 carbonyl group, and (iii) lytic cleavage of the O-4:C-4 bonding that is facilitated by proton donation from a catalytic acid <cite>Lombard2010</cite>. Please see the following reviews on PL classification, specificities, and structures <cite>Lombard2010 Garron2010</cite>. | + | Polysaccharide lyases (PLs) cleave uronic acid-containing polysaccharides via a β-elimination mechanism to generate an unsaturated hexenuronic acid residue and a new reducing end at the point of cleavage <cite>Lombard2010 Garron2010</cite>. PLs have been grouped into families and subfamilies within the Carbohydrate-Active Enzyme (CAZy) framework and that the PLs included are restricted to those operating via ''syn''- and ''anti''-elimination mechanisms <cite>Lombard2010</cite>. In this way, they are distinct from carbon-oxygen lyases that modify polysaccharide composition. Broadly, the mechanism of PL action can be described as consisting of three events: (i) abstraction of the C-5 proton on the sugar ring of a uronic acid or ester by a charge stabilizing cation such as Ca<sup>2+</sup> or a basic amino acid side chain, (ii) stabilization of the resulting anion by charge delocalization onto the C-6 carbonyl group, and (iii) lytic cleavage of the O-4:C-4 bonding that is facilitated by proton donation from a catalytic acid <cite>Lombard2010 YipWithers2006</cite>. Please see the following reviews on PL classification, specificities, mechanisms, and structures <cite>Lombard2010 Garron2010 Garron2014 YipWithers2006</cite>. |
== References == | == References == | ||
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#Lombard2010 pmid=20925655 | #Lombard2010 pmid=20925655 | ||
#Garron2010 pmid=20805221 | #Garron2010 pmid=20805221 | ||
| + | #Garron2014 pmid=25156747 | ||
| + | #YipWithers2006 pmid=16495121 | ||
</biblio> | </biblio> | ||
[[Category:Definitions and explanations]] | [[Category:Definitions and explanations]] | ||
Revision as of 09:52, 10 October 2014
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- Author: ^^^Michael Suits^^^ and ^^^Wade Abbott^^^
- Responsible Curator: ^^^Spencer Williams^^^
Introduction
Polysaccharide lyases (PLs) cleave uronic acid-containing polysaccharides via a β-elimination mechanism to generate an unsaturated hexenuronic acid residue and a new reducing end at the point of cleavage [1, 2]. PLs have been grouped into families and subfamilies within the Carbohydrate-Active Enzyme (CAZy) framework and that the PLs included are restricted to those operating via syn- and anti-elimination mechanisms [1]. In this way, they are distinct from carbon-oxygen lyases that modify polysaccharide composition. Broadly, the mechanism of PL action can be described as consisting of three events: (i) abstraction of the C-5 proton on the sugar ring of a uronic acid or ester by a charge stabilizing cation such as Ca2+ or a basic amino acid side chain, (ii) stabilization of the resulting anion by charge delocalization onto the C-6 carbonyl group, and (iii) lytic cleavage of the O-4:C-4 bonding that is facilitated by proton donation from a catalytic acid [1, 3]. Please see the following reviews on PL classification, specificities, mechanisms, and structures [1, 2, 3, 4].
References
- Lombard V, Bernard T, Rancurel C, Brumer H, Coutinho PM, and Henrissat B. (2010). A hierarchical classification of polysaccharide lyases for glycogenomics. Biochem J. 2010;432(3):437-44. DOI:10.1042/BJ20101185 |
- Garron ML and Cygler M. (2010). Structural and mechanistic classification of uronic acid-containing polysaccharide lyases. Glycobiology. 2010;20(12):1547-73. DOI:10.1093/glycob/cwq122 |
- Yip VL and Withers SG. (2006). Breakdown of oligosaccharides by the process of elimination. Curr Opin Chem Biol. 2006;10(2):147-55. DOI:10.1016/j.cbpa.2006.02.005 |
- Garron ML and Cygler M. (2014). Uronic polysaccharide degrading enzymes. Curr Opin Struct Biol. 2014;28:87-95. DOI:10.1016/j.sbi.2014.07.012 |