The biosynthesis of raucaffrinoline from perakine is a side route of the ajmaline biosynthesis pathway. The enzyme is a member of the aldo-keto reductase enzyme superfamily from higher plants.
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The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
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SYSTEMATIC NAME
IUBMB Comments
raucaffrinoline:NADP+ oxidoreductase
The biosynthesis of raucaffrinoline from perakine is a side route of the ajmaline biosynthesis pathway. The enzyme is a member of the aldo-keto reductase enzyme superfamily from higher plants.
NADPH can not be replaced by NADH. In presence of the oxidized cofactor NADP+ the reverse reaction of the reductase is low, with less than 0.5% relative activity of the forward reaction
probable dual functionality of perakine reductase, which may not only include alkaloid biosynthesis but may also include function in phenylpropanoid metabolism, generating cinnamic alcohols
enantioselective 1,2-reduction of alpha,beta-unsaturated ketones and aryl ketones by perakine reductase. Perakine reductase catalyzes asymmetric reduction of enones and aromatic ketones, leading to alpha-allylic alcohols and alpha-aromatic alcohols. It is NADPH-dependent. Among the evaluated substances, 4'-nitroacetophenone is found to be the best ketone substrate, with yield and enantiomeric excess values exceeding 99%. Exclusive enantioselectivity of enzyme perakine reductase (PR)
perakine reductase catalyzes the NADPH-dependent reduction of the aldehyde perakine to yield the alcohol raucaffrinoline in the biosynthetic pathway of ajmaline in Rauvolfia, a key step in indole alkaloid biosynthesis
the enzyme belongs to the AKR13D subfamily of the aldo-keto reductases, evolutionary relationship of AKR13D from Rauvolfia serpentina to annotated AKR families and subfamilies
the active site is formed by the catalytic tetrad Asp52, Tyr57, Lys84, and His126 at the center of the (alpha/beta)8-barrel structure. Upon NADPH binding, dramatic conformational changes and movements are observed: two additional beta-strands in the C terminus become ordered to form one alpha-helix, and a movement of up to 24 A occurs. This conformational change creates a large space that allows the binding of substrates of variable size for PR and enhances the enzyme activity
molecular modeling of the reaction mechansim. In the model, the oxygen atom of the product's hydroxy group approaches the carboxamide group of NADPH, located within a hydrogen-bond distance of the gamma-N of the imidazole ring of His126. Substrate binding analysis: the large pocket is formed by the surface of residues Ile56, Ile87, Ile 90, His126, and Arg127, the three clustered Ile residues contributing to the hydrophobic property of the pocket may facilitate substrate binding, the small pocket comprises the surface of the Met21, Tyr57, and Lys84 residues, together with the nicotinamide riboside component of NADPH
three-dimensional structure modeling of wild-type and mutant apo methylated enzymes with (alpha/beta)8-barrels with eight parallel beta-strands and eight alpha-helices typical for AKR superfamily members, overview
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
crystals of the purified and methylated enzyme are obtained by the hanging-drop vapour diffusion technique at 20°C with 100 mM sodium citrate pH 5.6 and 27% PEG 4000 as precipitant. Crystals belong to space group C2221 and diffract to 2.0 A, with unit-cell parameters a = 58.9, b = 93.0, c = 143.4 A
purified recombinant methylated His6-tagged enzyme wild-type and mutant A213W, hanging drop vapor diffusion method, mixing of 0.002 ml of 5.5 mg/ml protein in 10 mM Tris-HCl buffer, pH 7.0, 1 mM DTT, 10 mM EDTA, with 0002 ml reservoir solution containing 25% v/v PEG 4000, 0.1 mM sodium citrate, pH 5.6, equilibration against 1 ml of reservoir solution at 20°C for 7 days, X-ray diffraction structure determination and analysis at 2.31 A and 1.77 A resolution, respectively
site-directed mutagenesis of each of the functional residues of catalytic tetrad Asp52, Tyr57, Lys84, His126 to an alanine residue results in more than 97.8% loss of enzyme activity
site-directed mutagenesis of each of the functional residues of catalytic tetrad Asp52, Tyr57, Lys84, His126 to an alanine residue results in more than 97.8% loss of enzyme activity
Rosenthal, C.; Mueller, U.; Panjikar, S.; Sun, L.; Ruppert, M.; Zhao, Y.; Stckigt, J.
Expression, purification, crystallization and preliminary X-ray analysis of perakine reductase, a new member of the aldo-keto reductase enzyme superfamily from higher plants
Sun, L.; Ruppert, M.; Sheludko, Y.; Warzecha, H.; Zhao, Y.; Stckigt, J.
Purification, cloning, functional expression and characterization of perakine reductase: the first example from the AKR enzyme family, extending the alkaloidal network of the plant Rauvolfia
Sun, L.; Chen, Y.; Rajendran, C.; Mueller, U.; Panjikar, S.; Wang, M.; Mindnich, R.; Rosenthal, C.; Penning, T.M.; Stoeckigt, J.
Crystal structure of perakine reductase, founding member of a novel aldo-keto reductase (AKR) subfamily that undergoes unique conformational changes during NADPH binding