Activating Compound | Comment | Organism | Structure |
---|---|---|---|
Triton X-100 | up to 0.03% Triton X-100 in the assay mixture, the catalytic activity is enhanced | Withania somnifera |
Inhibitors | Comment | Organism | Structure |
---|---|---|---|
Co2+ | strongly inhibits the sterol glucosyltransferase activity, IC50 (mM): 1.3 | Withania somnifera | |
GTP | the inhibitory effect of GTP is less prominent as compared to UDP | Withania somnifera | |
Hg2+ | strongly inhibits the sterol glucosyltransferase activity, IC50 (mM): 0.5 | Withania somnifera | |
iodoacetamide | strong and irreversible inhibition by thiol directed reagents like 4-chloromercuribenzoate, N-methylmaleimide and iodoacetamide suggest the requirement of free-SH groups for the catalytic activity | Withania somnifera | |
N-ethylmaleimide | strong and irreversible inhibition by thiol directed reagents like 4-chloromercuribenzoate, N-methylmaleimide and iodoacetamide suggest the requirement of free-SH groups for the catalytic activity | Withania somnifera | |
Ni2+ | strongly inhibits the sterol glucosyltransferase activity, IC50 (mM): 1.2 | Withania somnifera | |
p-chloromercuribenzoate | strong and irreversible inhibition by thiol directed reagents like 4-chloromercuribenzoate, N-methylmaleimide and iodoacetamide suggest the requirement of free-SH groups for the catalytic activity | Withania somnifera | |
Triton X-100 | at higher levels (0.3%), Triton X-100 inactivats the enzyme, giving 10% of the original activity after 30 min pre-incubation | Withania somnifera | |
UDP | the inhibitory effect of UTP and GTP is less prominent as compared to UDP | Withania somnifera | |
UTP | the inhibitory effect of UTP is less prominent as compared to UDP | Withania somnifera | |
Zn2+ | strongly inhibits the sterol glucosyltransferase activity, IC50 (mM): 0.04 | Withania somnifera |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.002 | - |
diosgenin | for the cytosolic enzyme | Withania somnifera | |
0.005 | - |
pregnenolone | for the cytosolic enzyme | Withania somnifera | |
0.005 | - |
beta-sitosterol | for the cytosolic enzyme | Withania somnifera | |
0.006 | - |
3-beta-hydroxy-pregna-5,16-dien-20-one | for the cytosolic enzyme | Withania somnifera | |
0.014 | - |
UDP-glucose | for the cytosolic enzyme | Withania somnifera | |
0.024 | - |
24-methylene cholesterol | for the cytosolic enzyme | Withania somnifera | |
0.119 | - |
dehydroepiandrosterone | for the cytosolic enzyme | Withania somnifera | |
0.125 | - |
stigmasterol | for the cytosolic enzyme | Withania somnifera |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
additional information | Mg2+, Mn2+, Ca2+, Co2+ do not show any effect | Withania somnifera |
Molecular Weight [Da] | Molecular Weight Maximum [Da] | Comment | Organism |
---|---|---|---|
37000 | - |
SDS-PAGE | Withania somnifera |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Withania somnifera | - |
- |
- |
Purification (Comment) | Organism |
---|---|
Cibacron Blue column, Sephadex G-25 column and Mono Q anion exchange column | Withania somnifera |
Source Tissue | Comment | Organism | Textmining |
---|---|---|---|
leaf | - |
Withania somnifera | - |
Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
---|---|---|---|
additional information | - |
the cytosolic enzyme shows 100% activity with 24-methylene chloseterol as substrate. Using Dehydroepiandrosterone, Stigmasterol, Brassicasterol, beta-sitosterol or Deacetyl-16-DPA the activtity is 75% - 44%. Using Diosgenin, Solasdine or Pregnenolene the activity is 31,5% - 14.1%. Using Cholesterol, 20S,22R-1alpha, 3beta-dihydroxy-witha-5,24-dienolide, Hecogenin, Tigogenin, Quercetin or Daidzein the activity is 8.9% - 2.1%. There is no activity, when using Euphol, Ursolic acid, Testosterone, Estradiol or Single glucose withanolide as substrate. Sterol glucosyltransferase activity is monitored radiometricaly using UDP-[U-14C] glucose as the radioactive substrate in the radioactive substrate | Withania somnifera |
additional information | - |
the membrane bound enzyme shows 100% activity with 24-methylene chloseterol as substrate. Using Deacetyl-16-DPA, beta-sitosterol, Brassicasterol, Dehydroepiandrosterone, Pregnenolene, Stigmasterol or Cholesterol the activtity is 577% - 124%. The enzyme shows 2% activity with Diosgenin as substrate. It does not show any activity with Solasodine 16,17alpha-epoxy prednenolene, Hecogenin, 20S,22R-1alpha, 3beta-dihydroxy-witha-5,24-dienolide, Tigogenin, Quercetin, Daidzein, Euphol, Ursolic acid, Testosterone, Estradiol or Single glucose withanolide. | Withania somnifera |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
24-methylene cholesterol + UDP-glucose | - |
Withania somnifera | UDP + 24-methylene-cholesterol 3-beta-D-glucoside | - |
? | |
3beta-hydroxy-pregna-5,16-dien-20-one + UDP-glucose | - |
Withania somnifera | UDP + 3beta-20-oxopregna-5,16-dien-3-yl beta-D-glucopyranoside | - |
? | |
beta-sitosterol + UDP-glucose | - |
Withania somnifera | UDP + beta-sitosterol 3-beta-D-glucoside | - |
? | |
dehydroepiandrosterone + UDP-glucose | - |
Withania somnifera | UDP + dehydroepiandrosterone 3-beta-D-glucoside | - |
? | |
diosgenin + UDP-glucose | - |
Withania somnifera | UDP + diosgenin 3-beta-D-glucoside | - |
? | |
additional information | the enzyme is highly specific to sterols and shows no activity with non steroidal substrates. Amongst the sterols, the enzyme is position specific and works only with C-3 hydroxyl sterols, but the extradiol C-3 hydroxyl group is not glucosylated. Sterols with A-B ring 5-en (e.g. deacetyl-16-DPA) are glucosylated more efficiently than those with 5alpha-H. For the cytosolic enzyme, the relative substrate specificity of the membrane-bound enzyme is different. The membrane enzyme is more specific towards phytosterols and brassicasterol. It shows no activity towards secondary metabolits and flavonoids and isoflavonoids. | Withania somnifera | ? | - |
? | |
pregnenolone + UDP-glucose | - |
Withania somnifera | UDP + pregnenolone 3-beta-D-glucoside | - |
? | |
stigmasterol + UDP-glucose | - |
Withania somnifera | UDP + stigmasterol 3-beta-D-glucoside | - |
? |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
30 | - |
- |
Withania somnifera |
Turnover Number Minimum [1/s] | Turnover Number Maximum [1/s] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.0023 | - |
diosgenin | for the cytosolic enzyme | Withania somnifera | |
0.0037 | - |
beta-sitosterol | for the cytosolic enzyme | Withania somnifera | |
0.0047 | - |
pregnenolone | for the cytosolic enzyme | Withania somnifera | |
0.0072 | - |
dehydroepiandrosterone | for the cytosolic enzyme | Withania somnifera | |
0.0087 | - |
UDP-glucose | for the cytosolic enzyme | Withania somnifera | |
0.0088 | - |
stigmasterol | for the cytosolic enzyme | Withania somnifera | |
0.0093 | - |
3-beta-hydroxy-pregna-5,16-dien-20-one | for the cytosolic enzyme | Withania somnifera | |
0.38 | - |
24-methylene cholesterol | for the cytosolic enzyme | Withania somnifera |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
8 | - |
- |
Withania somnifera |
pH Minimum | pH Maximum | Comment | Organism |
---|---|---|---|
7 | 9 | the enzyme has an optimum pH for activity around 8.0 with half maximal activities at 7.0 and above 9.0 | Withania somnifera |
Organism | Comment | pI Value Maximum | pI Value |
---|---|---|---|
Withania somnifera | determined by chromatofocusing | - |
3.8 |
IC50 Value | IC50 Value Maximum | Comment | Organism | Inhibitor | Structure |
---|---|---|---|---|---|
0.04 | - |
strongly inhibits the sterol glucosyltransferase activity, IC50 (mM): 0.04 | Withania somnifera | Zn2+ | |
0.5 | - |
strongly inhibits the sterol glucosyltransferase activity, IC50 (mM): 0.5 | Withania somnifera | Hg2+ | |
1.2 | - |
strongly inhibits the sterol glucosyltransferase activity, IC50 (mM): 1.2 | Withania somnifera | Ni2+ | |
1.3 | - |
strongly inhibits the sterol glucosyltransferase activity, IC50 (mM): 1.3 | Withania somnifera | Co2+ |