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Literature summary for 5.4.99.39 extracted from
- beta-Amyrin synthase from Euphorbia tirucalli L. functional analyses of the highly conserved aromatic residues Phe413, Tyr259 and Trp257 disclose the importance of the appropriate steric bulk, and cation-Pi and CH-Pi interactions for the efficient catalytic (2017), Org. Biomol. Chem., 15, 177-188 .
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| gene EtAS, sequence comparisons, recombinant expression of wild-type and mutant enzymes in yeast | Euphorbia tirucalli |
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| F413A | site-directed mutagenesis, functional analysis, the mutant shows slightly reduced activity compared to thre wild-type enzyme | Euphorbia tirucalli |
| F413H | site-directed mutagenesis, functional analysis, the mutant shows slightly increased activity compared to thre wild-type enzyme | Euphorbia tirucalli |
| F413M | site-directed mutagenesis, functional analysis, the mutant shows slightly reduced activity compared to thre wild-type enzyme | Euphorbia tirucalli |
| F413S | site-directed mutagenesis, functional analysis, the mutant shows slightly increased activity compared to thre wild-type enzyme | Euphorbia tirucalli |
| F413T | site-directed mutagenesis, functional analysis, the mutant shows slightly increased activity compared to thre wild-type enzyme | Euphorbia tirucalli |
| F413V | site-directed mutagenesis, functional analysis, the mutant shows slightly reduced activity compared to thre wild-type enzyme | Euphorbia tirucalli |
| F413W | site-directed mutagenesis, functional analysis, the mutant shows slightly increased activity compared to thre wild-type enzyme | Euphorbia tirucalli |
| F413Y | site-directed mutagenesis, functional analysis, the mutant shows slightly reduced activity compared to thre wild-type enzyme | Euphorbia tirucalli |
| additional information | quantities of oleanane-type, 17-epi-dammarane-type, and dammarane-type triterpenes in cultures of wild-type and mutant strains differ significantly, overview | Euphorbia tirucalli |
| Y259A | site-directed mutagenesis, functional analysis | Euphorbia tirucalli |
| Y259F | site-directed mutagenesis, functional analysis | Euphorbia tirucalli |
| Y259H | site-directed mutagenesis, functional analysis | Euphorbia tirucalli |
| Y259L | site-directed mutagenesis, functional analysis | Euphorbia tirucalli |
| Y259V | site-directed mutagenesis, functional analysis | Euphorbia tirucalli |
| Y259W | site-directed mutagenesis, functional analysis | Euphorbia tirucalli |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| (3S)-2,3-epoxy-2,3-dihydrosqualene | Euphorbia tirucalli | - |
beta-amyrin | - |
r |  |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Euphorbia tirucalli | Q401R6 | - |
- |
Reaction
| Reaction | Comment | Organism | Reaction ID |
|---|---|---|---|
| (3S)-2,3-epoxy-2,3-dihydrosqualene = beta-amyrin | the Phe416 residue is located near the D-ring formation site and works to position the oxidosqualene substrate correctly within the reaction cavity. On the other hand, the major catalysis-related function of the Tyr259 and Trp257 residues is to yield their Pi-electrons to the cationic intermediate | Euphorbia tirucalli |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| (3S)-2,3-epoxy-2,3-dihydrosqualene | - |
Euphorbia tirucalli | beta-amyrin | - |
r | |
| additional information | product identification by EIMS and NMR spectral analyses | Euphorbia tirucalli | ? | - |
? | |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| EtAS | - |
Euphorbia tirucalli |
General Information
| General Information | Comment | Organism |
|---|---|---|
| malfunction | the Y259F variant shows nearly equivalent activity to that of the wild type, but aliphatic mutants such as the Ala, Val, and Leu variants show significantly decreased activity and yield the tetracyclic dammarane scaffold. The aliphatic variants of Trp257 exhibit remarkably decreased enzymatic activity, and lupeol is produced in a high production ratio. The aromatic Phe and Tyr mutants exhibit high activities owing to their more increased Pi-electron density relative to that of the aliphatic mutants, but lupeol is produced in a significantly high yield besides beta-amyrin. The Trp residue is likely to be responsible for the robust binding of Me-30 through CH-Pi interaction. The decreased Pi-electron density of the Phe and Tyr mutants compared to that of Trp results in the high production of lupeol | Euphorbia tirucalli |
| additional information | the highly conserved aromatic residues Phe413, Tyr259 and Trp257 disclose the importance of the appropriate steric bulk, and cation-Pi and CH-Pi interactions for the efficient catalytic action of the polyolefin cyclization cascade, functional analysis, overview. Homology modeling of beta-amyrin synthase using the X-ray crystal structure of human lanosterol cyclase, PDB ID 1w6k, as template. Structure comparisons. The Tyr259 residue stabilizes the baccharenyl secondary cation via cation-Pi interaction, residue Trp257 stabilizes the oleanyl cation via cation-Pi interaction | Euphorbia tirucalli |
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