1ju2
From Proteopedia
(New page: 200px<br /><applet load="1ju2" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ju2, resolution 1.47Å" /> '''Crystal structure of...) |
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| - | [[Image:1ju2.jpg|left|200px]]<br /><applet load="1ju2" size=" | + | [[Image:1ju2.jpg|left|200px]]<br /><applet load="1ju2" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1ju2, resolution 1.47Å" /> | caption="1ju2, resolution 1.47Å" /> | ||
'''Crystal structure of the hydroxynitrile lyase from almond'''<br /> | '''Crystal structure of the hydroxynitrile lyase from almond'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Cyanogenesis is a defense process of several thousand plant | + | BACKGROUND: Cyanogenesis is a defense process of several thousand plant species. Hydroxynitrile lyase, a key enzyme of this process, cleaves a cyanohydrin into hydrocyanic acid and the corresponding aldehyde or ketone. The reverse reaction constitutes an important tool in biocatalysis. Different classes of hydroxynitrile lyases have convergently evolved from FAD-dependent oxidoreductases, alpha/beta hydrolases, and alcohol dehydrogenases. The FAD-dependent hydroxynitrile lyases (FAD-HNLs) carry a flavin cofactor whose redox properties appear to be unimportant for catalysis. RESULTS: We have determined the crystal structure of a 61 kDa hydroxynitrile lyase isoenzyme from Prunus amygdalus (PaHNL1) to 1.5 A resolution. Clear electron density originating from four glycosylation sites could be observed. As concerns the overall protein fold including the FAD cofactor, PaHNL1 belongs to the family of GMC oxidoreductases. The active site for the HNL reaction is probably at a very similar position as the active sites in homologous oxidases. CONCLUSIONS: There is strong evidence from the structure and the reaction product that FAD-dependent hydroxynitrile lyases have evolved from an aryl alcohol oxidizing precursor. Since key residues implicated in oxidoreductase activity are also present in PaHNL1, it is not obvious why this enzyme shows no oxidase activity. Similarly, features proposed to be relevant for hydroxy-nitrile lyase activity in other hydroxynitrile lyases, i.e., a general base and a positive charge to stabilize the cyanide, are not obviously present in the putative active site of PaHNL1. Therefore, the reason for its HNL activity is far from being well understood at this point. |
==About this Structure== | ==About this Structure== | ||
| - | 1JU2 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Prunus_dulcis Prunus dulcis] with NAG, FAD and IPA as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Mandelonitrile_lyase Mandelonitrile lyase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.1.2.10 4.1.2.10] Full crystallographic information is available from [http:// | + | 1JU2 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Prunus_dulcis Prunus dulcis] with <scene name='pdbligand=NAG:'>NAG</scene>, <scene name='pdbligand=FAD:'>FAD</scene> and <scene name='pdbligand=IPA:'>IPA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Mandelonitrile_lyase Mandelonitrile lyase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.1.2.10 4.1.2.10] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1JU2 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: hydroxynitrile lyase]] | [[Category: hydroxynitrile lyase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:26:45 2008'' |
Revision as of 11:26, 21 February 2008
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Crystal structure of the hydroxynitrile lyase from almond
Overview
BACKGROUND: Cyanogenesis is a defense process of several thousand plant species. Hydroxynitrile lyase, a key enzyme of this process, cleaves a cyanohydrin into hydrocyanic acid and the corresponding aldehyde or ketone. The reverse reaction constitutes an important tool in biocatalysis. Different classes of hydroxynitrile lyases have convergently evolved from FAD-dependent oxidoreductases, alpha/beta hydrolases, and alcohol dehydrogenases. The FAD-dependent hydroxynitrile lyases (FAD-HNLs) carry a flavin cofactor whose redox properties appear to be unimportant for catalysis. RESULTS: We have determined the crystal structure of a 61 kDa hydroxynitrile lyase isoenzyme from Prunus amygdalus (PaHNL1) to 1.5 A resolution. Clear electron density originating from four glycosylation sites could be observed. As concerns the overall protein fold including the FAD cofactor, PaHNL1 belongs to the family of GMC oxidoreductases. The active site for the HNL reaction is probably at a very similar position as the active sites in homologous oxidases. CONCLUSIONS: There is strong evidence from the structure and the reaction product that FAD-dependent hydroxynitrile lyases have evolved from an aryl alcohol oxidizing precursor. Since key residues implicated in oxidoreductase activity are also present in PaHNL1, it is not obvious why this enzyme shows no oxidase activity. Similarly, features proposed to be relevant for hydroxy-nitrile lyase activity in other hydroxynitrile lyases, i.e., a general base and a positive charge to stabilize the cyanide, are not obviously present in the putative active site of PaHNL1. Therefore, the reason for its HNL activity is far from being well understood at this point.
About this Structure
1JU2 is a Single protein structure of sequence from Prunus dulcis with , and as ligands. Active as Mandelonitrile lyase, with EC number 4.1.2.10 Full crystallographic information is available from OCA.
Reference
The hydroxynitrile lyase from almond: a lyase that looks like an oxidoreductase., Dreveny I, Gruber K, Glieder A, Thompson A, Kratky C, Structure. 2001 Sep;9(9):803-15. PMID:11566130
Page seeded by OCA on Thu Feb 21 13:26:45 2008
Categories: Mandelonitrile lyase | Prunus dulcis | Single protein | Dreveny, I. | Glieder, A. | Gruber, K. | Kratky, C. | Thompson, A. | FAD | IPA | NAG | Almond | Cyanogenesis | Flavin | Gmc oxidoreductase | Hydroxynitrile lyase
