Polyneuridine-aldehyde esterase
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| polyneuridine-aldehyde esterase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 Polyneuridine-Aldehyde Esterase 3D Rendering | |||||||||
| Identifiers | |||||||||
| EC no. | 3.1.1.78 | ||||||||
| CAS no. | 87041-55-2 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
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The enzyme polyneuridine-aldehyde esterase (EC 3.1.1.78) catalyzes the following reaction:[1]
- polyneuridine aldehyde + H2O 16-epivellosimine + CO2 + methanol
This enzyme participates in indole and ipecac alkaloid biosynthesis.
Nomenclature[edit]
This enzyme belongs to the family of hydrolases, specifically those acting on carboxylic ester bonds. The systematic name is polyneuridine aldehyde hydrolase (decarboxylating). Other names in common use include:
- polyneuridine aldehyde esterase
- PNAE
Homologues[edit]
This enzyme is found in various forms in plant species such as Arabidopsis thaliana, Glycine max (soybean), Vitis vinifera (wine grape), and Solanum lycopersicum (tomato) among others.
Polyneuridine-aldehyde esterase also appears in select bacteria including Enterobacter cloacae.
Structure[edit]
The secondary structure of this enzyme consists mainly of α helices. In its native form, this enzyme has a tertiary structure that includes two main lobes (as depicted above in the blue 3D representation on the top right).
Reaction[edit]
 |  |  |
![{\displaystyle {\xrightarrow[{+H_{2}O\ -CH_{3}OH}]{polyneuridine-aldehyde\ esterase}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/c531b2f1ef50a92e2bc339985a2930889e6e7c00)
![{\displaystyle {\xrightarrow[{-CO_{2}}]{}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/b07e25d5081c7cd1888da626b44147b66762db17)
Polyneuridine-aldehyde esterase catalyzes the hydrolysis of the methyl ester in polyneuridine aldehyde to form polyneuridine β-aldehydoacid and methanol. The carboxylic acid in the product spontaneously undergoes decarboxylation, yielding 16-epivellosimine and carbon dioxide.[1]
Mechanism[edit]
The mechanism of hydrolysis performed by polyneuridine-aldehyde esterase is not known. It has been suggested that the enzyme utilizes a catalytic triad composed of Ser-87, Asp-216 and His-244.[3] The catalytic amino acid order is the same as the order of enzymes that are part of the α/β hydrolase family. Thus polyneuridine-aldehyde esterase may be a novel member of the α/β hydrolase group.[4]
Broader significance[edit]
This enzyme is a part of the pathway of indole alkaloid biosynthesis. The indole alkaloids that result from this metabolic pathway are used by many plant species as a defense against herbivores and parasites.
Open questions[edit]
The precise mechanisms by which this enzyme performs its function is still unknown. As noted above, researchers are formulating suggestions as to how polyneuridine-aldehyde esterase catalyses the decomposition of polyneuridine-aldehyde, but a mechanism has not yet been affirmed with absolute certainty. Due to the lack of complete understanding of polyneuridine-aldehyde esterase's precise mechanism, this enzyme cannot be grouped into a family of enzymes. Based on mechanism theories, suggestions can be made as to how this enzyme should be categorized, and some parallels can be drawn between polyneuridine-aldehyde esterase and other enzymes.
References[edit]
- ^ a b Pfitzner A, Stöckigt J (August 1983). "Characterization of polyneuridine aldehyde esterase, a key enzyme in the biosynthesis of sarpagine/ajmaline type alkaloids". Planta Med. 48 (8): 221–7. doi:10.1055/s-2007-969924. PMID 17404987.
- ^ PDB: 3GZJ; Yang L, Hill M, Wang M, Panjikar S, Stöckigt J (2009). "Structural basis and enzymatic mechanism of the biosynthesis of C9- from C10-monoterpenoid indole alkaloids". Angew. Chem. Int. Ed. Engl. 48 (28): 5211–3. doi:10.1002/anie.200900150. PMID 19496101.
- ^ Mattern-Dogru E, Ma X, Hartmann J, Decker H, Stöckigt J (June 2002). "Potential active-site residues in polyneuridine aldehyde esterase, a central enzyme of indole alkaloid biosynthesis, by modelling and site-directed mutagenesis". Eur. J. Biochem. 269 (12): 2889–96. doi:10.1046/j.1432-1033.2002.02956.x. PMID 12071952.
- ^ Dogru E, Warzecha H, Seibel F, Haebel S, Lottspeich F, Stöckigt J (March 2000). "The gene encoding polyneuridine aldehyde esterase of monoterpenoid indole alkaloid biosynthesis in plants is an ortholog of the alpha/betahydrolase super family". Eur. J. Biochem. 267 (5): 1397–406. doi:10.1046/j.1432-1327.2000.01136.x. PMID 10691977.
Further reading[edit]
- Pfitzner A, Stockigt J (1983). "Polyneuridine aldehyde esterase: an unusual specific enzyme involved in the biosynthesis of sarpagine type alkaloids". Journal of the Chemical Society, Chemical Communications (8): 459–460. doi:10.1039/C39830000459.
