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Literature summary extracted from
- Electrocatalytic hydroxylation of sterols by steroid C25 dehydrogenase from Sterolibacterium denitrificans (2018), Chemistry, 24, 7710-7717.
Protein Variants
| EC Number | Protein Variants | Comment | Organism |
|---|---|---|---|
| 1.17.99.10 | additional information | purified native S25DH is immobilized on a modified gold working electrode with the co-adsorbent chitosan. The complexes ferricyanide ([Fe(CN)6]3-) and ferrocenium methanol (FM+) are effective artificial electron acceptors from S25DH and act as mediators of electron transfer between the electrode and the enzyme. 2-Hydroxypropyl-beta-cyclodextrin (HPCD) is employed as a sterol solubiliser, in addition to 2-methoxyethanol. The catalytic activity varies, depending upon the concentration of solubiliser in the reaction mixture. Parallel studies with [Fe(CN)6]3- as a chemical (as opposed to electrochemical) oxidant coupled to HPLC analysis show that S25DH is capable of oxidising both vitD3 and its less stable isomer, pre-vitD3, and that the former substrate is stabilised by HPCD. Method evaluation and optimization, mediator and catalytic voltammetry, overview | Sterolibacterium denitrificans |
KM Value [mM]
| EC Number | KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|---|
| 1.17.99.10 | additional information | - |
additional information | Michaelis-Menten kinetics of immobilized enzyme on the Au/Hpyt/chitosan electrode | Sterolibacterium denitrificans | |
| 1.17.99.10 | 0.34 | - |
vitamin D3 | pH 7.5, 30°C, purified enzyme, immobilized enzyme | Sterolibacterium denitrificans |  |
| 1.17.99.10 | 1.2 | - |
cholest-4-en-3-one | pH 7.5, 30°C, purified enzyme, immobilized enzyme | Sterolibacterium denitrificans | |
Localization
| EC Number | Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|---|
| 1.17.99.10 | periplasm | - |
Sterolibacterium denitrificans | - |
- |
Natural Substrates/ Products (Substrates)
| EC Number | Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|---|
| 1.17.99.10 | cholest-4-en-3-one + acceptor + H2O | Sterolibacterium denitrificans | - |
25-hydroxycholest-4-en-3-one + reduced acceptor | - |
? | |
| 1.17.99.10 | vitamin D3 + acceptor + H2O | Sterolibacterium denitrificans | - |
25-hydroxyvitamin D3 + reduced acceptor | - |
? | |
Organism
| EC Number | Organism | UniProt | Comment | Textmining |
|---|---|---|---|---|
| 1.17.99.10 | Sterolibacterium denitrificans | H9NN89 AND H9NNA5 AND H9NN91 | S25DH subunits alpha, beta, and gamma, encoded by genes s25dA, s25dB7, and s25dC | - |
Purification (Commentary)
| EC Number | Purification (Comment) | Organism |
|---|---|---|
| 1.17.99.10 | native enzyme under aerobic conditions to homogeneity | Sterolibacterium denitrificans |
Reaction
| EC Number | Reaction | Comment | Organism | Reaction ID |
|---|---|---|---|---|
| 1.17.99.10 | cholest-4-en-3-one + acceptor + H2O = 25-hydroxycholest-4-en-3-one + reduced acceptor | mediated electrocatalytic mechanism of S25DH, and electrochemically driven S25DH sterol hydroxylation mediated by ferrocenium methanol (FM+) or [Fe(CN)6]3-, overview | Sterolibacterium denitrificans |
Substrates and Products (Substrate)
| EC Number | Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|---|
| 1.17.99.10 | cholest-4-en-3-one + acceptor + H2O | - |
Sterolibacterium denitrificans | 25-hydroxycholest-4-en-3-one + reduced acceptor | - |
? | |
| 1.17.99.10 | vitamin D3 + acceptor + H2O | - |
Sterolibacterium denitrificans | 25-hydroxyvitamin D3 + reduced acceptor | - |
? | |
| 1.17.99.10 | vitamin D3 + acceptor + H2O | enzyme S25DH is capable of oxidising both vitD3 and its less stable isomer, pre-vitD3 | Sterolibacterium denitrificans | 25-hydroxyvitamin D3 + reduced acceptor | - |
? | |
Subunits
| EC Number | Subunits | Comment | Organism |
|---|---|---|---|
| 1.17.99.10 | heterotrimer | alphabetagamma | Sterolibacterium denitrificans |
Synonyms
| EC Number | Synonyms | Comment | Organism |
|---|---|---|---|
| 1.17.99.10 | molybdoenzyme steroid C25 dehydrogenase | - |
Sterolibacterium denitrificans |
| 1.17.99.10 | S25DH | - |
Sterolibacterium denitrificans |
| 1.17.99.10 | steroid C25 dehydrogenase | - |
Sterolibacterium denitrificans |
Temperature Optimum [°C]
| EC Number | Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|---|
| 1.17.99.10 | 40 | - |
- |
Sterolibacterium denitrificans |
Temperature Range [°C]
| EC Number | Temperature Minimum [°C] | Temperature Maximum [°C] | Comment | Organism |
|---|---|---|---|---|
| 1.17.99.10 | 15 | 40 | barely any catalysis is observable at 15°C and an essentially reversible FM+/0 response is seen. The catalytic current increases considerably with temperature up to 40°C | Sterolibacterium denitrificans |
pH Optimum
| EC Number | pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|---|
| 1.17.99.10 | 7.5 | - |
assay at | Sterolibacterium denitrificans |
Cofactor
| EC Number | Cofactor | Comment | Organism | Structure |
|---|---|---|---|---|
| 1.17.99.10 | ferricyanide | [Fe(CN)6]3-, an artificial acceptor | Sterolibacterium denitrificans | |
| 1.17.99.10 | heme | the gamma-subunit contains a heme c with Lys/Met axial ligands | Sterolibacterium denitrificans | |
| 1.17.99.10 | molybdopterin | in the active site, the alpha-subunit contains the molybdenum active site and an unusual 4Fe-4S cluster with histidine ligation | Sterolibacterium denitrificans | |
| 1.17.99.10 | additional information | ferrocenium methanol (FM+), an artificial acceptor | Sterolibacterium denitrificans | |
| 1.17.99.10 | additional information | the heme cofactor is the site of electron egress from the enzyme following substrate oxidation at the active site, and the remaining intermediary Fe-S clusters are electron-relay centres | Sterolibacterium denitrificans | |
| 1.17.99.10 | [3Fe-4S] cluster | the alpha-subunit contains the molybdenum active site and an unusual 4Fe-4S cluster with histidine ligation. The beta-subunit contains three 4Fe-4S clusters (FS1-FS3) and a 3Fe-4S cluster (FS4) | Sterolibacterium denitrificans | |
| 1.17.99.10 | [4Fe-4S] cluster | the alpha-subunit contains the molybdenum active site and an unusual 4Fe-4S cluster with histidine ligation. The beta-subunit contains three 4Fe-4S clusters (FS1-FS3) and a 3Fe-4S cluster (FS4) | Sterolibacterium denitrificans | |
General Information
| EC Number | General Information | Comment | Organism |
|---|---|---|---|
| 1.17.99.10 | physiological function | the complex molybdoenzyme steroid C25 dehydrogenase (S25DH) from the beta-Proteobacterium Sterolibacterium denitrificans performs electrochemically driven catalysis of the oxygen-independent regioselective hydroxylation of the tertiary C25 atom of sterols and also their derivatives. Cholest-4-en-3-one is a native substrate for S25DH, which produces 25-hydroxycholest-4-en-3-one as a product of catalytic turnover. S25DH also shows catalytic activity with other important sterols, including 3-ketosterols, 3-hydroxysterols, 3-hydroxysterol esters and cholecalciferol (vitD3), which share the same hydrophobic tail | Sterolibacterium denitrificans |
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