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Literature summary for 1.1.1.270 extracted from
- Solubilization and partial purification of a microsomal 3-ketosteroid reductase of cholesterol biosynthesis (1981), Arch. Biochem. Biophys., 211, 430-438.
Activating Compound
| Activating Compound | Comment | Organism | Structure |
|---|---|---|---|
| cytosolic Z protein | fatty acid-binding protein, membrane-bound enzyme, twofold to threefold activation, stimulatory activity is lost after solubilization of microsomal enzyme. Stimulation reversed by titration of Z-protein with either fatty acids or anti-Z-protein immunoglobulin. Stimulation not restored by incorporating partially purified reductase into an artificial phospholipid membrane | Rattus norvegicus | |
| additional information | no activation by greatly increasing detergent concentration, Triton WR-1339, to a final concentration of 0.6%, no or poor activation by intestinal bile acid sequestrant, cholestyramine, no activation by bovine serum albumin | Rattus norvegicus |
Application
| Application | Comment | Organism |
|---|---|---|
| analysis | enzyme can be used for reconstitution of 4-methyl sterol demethylations of cholesterol biosynthesis from lanosterol | Rattus norvegicus |
General Stability
| General Stability | Organism |
|---|---|
| enzyme extreme labile | Rattus norvegicus |
| enzyme stable in presence of high concentrations of detergents | Rattus norvegicus |
| ethylene glycol stabilizes | Rattus norvegicus |
| stable against subtilisin VII, no attendent loss of 3-ketoreductase activity | Rattus norvegicus |
Inhibitors
| Inhibitors | Comment | Organism | Structure |
|---|---|---|---|
| ionic detergents | inactivation by strong solutions of ionic detergents, ethylene glycol minimizes inactivation | Rattus norvegicus | |
| additional information | no inhibition by greatly increasing detergent concentration, Triton WR-1339, to a final concentration of 0.6% | Rattus norvegicus |
KM Value [mM]
| KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| 0.078 | - |
4alpha-methyl-5alpha-cholest-7-en-3-one | solubilized enzyme | Rattus norvegicus |  |
| 0.236 | - |
4alpha-methyl-5alpha-cholest-7-en-3-one | microsomal-bound enzyme | Rattus norvegicus | |
Localization
| Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|
| membrane | membrane-bound | Rattus norvegicus | 16020 | - |
| microsome | microsomal-bound | Rattus norvegicus | - |
- |
Molecular Weight [Da]
| Molecular Weight [Da] | Molecular Weight Maximum [Da] | Comment | Organism |
|---|---|---|---|
| additional information | - |
chromatography on Sepharose 2B column shows ketoreductase activity eluted as high-molecular-weight complex | Rattus norvegicus |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| additional information | Rattus norvegicus | catalyzes NADPH-dependent reduction of 3-ketosteroid intermediates, 4-methyl sterol intermediates, of cholesterol biosynthesis from lanosterol, regenerates 3beta-hydroxy sterol | ? | - |
? | |
| additional information | Rattus norvegicus | enzyme of cholesterol biosynthesis | ? | - |
? | |
| additional information | Rattus norvegicus | involved in the 10-step oxidative removal of the 4-gem-dimethyl group of sterols | ? | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Rattus norvegicus | - |
male sprague-dawley rats | - |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| solubilization with Lubrol-WX in the presence of cholic acid, and partial purification | Rattus norvegicus |
Source Tissue
| Source Tissue | Comment | Organism | Textmining |
|---|---|---|---|
| liver | - |
Rattus norvegicus | - |
Specific Activity [micromol/min/mg]
| Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
|---|---|---|---|
| 0.0014 | - |
partially purified enzyme | Rattus norvegicus |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| 4,4-gem-dimethyl-5alpha-cholest-7-en-3-one + NADPH | - |
Rattus norvegicus | 4,4-gem-dimethyl-5alpha-cholest-7-en-3beta-ol + NADP+ | - |
? | |
| 4alpha-methyl-5alpha-cholest-7-en-3-one + NADPH | best substrate, reduction consistently about two times greater for monosubstituted steroid | Rattus norvegicus | 4alpha-methyl-5alpha-cholest-7-en-3beta-ol + NADP+ | - |
? | |
| additional information | substrate specificity | Rattus norvegicus | ? | - |
? | |
| additional information | sterol substrate specificity with 4alpha-monomethyl- and 4,4-dimethyl-3-ketosteroids | Rattus norvegicus | ? | - |
? | |
| additional information | catalyzes NADPH-dependent reduction of 3-ketosteroid intermediates, 4-methyl sterol intermediates, of cholesterol biosynthesis from lanosterol, regenerates 3beta-hydroxy sterol | Rattus norvegicus | ? | - |
? | |
| additional information | enzyme of cholesterol biosynthesis | Rattus norvegicus | ? | - |
? | |
| additional information | involved in the 10-step oxidative removal of the 4-gem-dimethyl group of sterols | Rattus norvegicus | ? | - |
? | |
Temperature Optimum [°C]
| Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 37 | - |
assay at | Rattus norvegicus |
pH Optimum
| pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|
| 7.4 | - |
assay at | Rattus norvegicus |
Cofactor
| Cofactor | Comment | Organism | Structure |
|---|---|---|---|
| additional information | essentially inactive with NADH | Rattus norvegicus | |
| NADPH | specific for NADPH, NADH is essentially inactive, less than 10% | Rattus norvegicus | |
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