Print
presqualene diphosphate synthase
Pathways
cholesterol biosynthesis (BRENDA)
:= BRENDA, 
:= KEGG, 
:= MetaCyc, 
:= SABIO-RK
:= amino acid sequences 
:= show the reaction diagram
EC Number
Reaction
Pathways
Reaction IDs
Stoichiometry Check
Missing Substrate
Missing Product
Commentary
Remark
2 (2E,6E)-farnesyl diphosphate = diphosphate + presqualene diphosphate
; "show the reaction diagram")
-
-
-
: first step of two-step reaction (R06223, R00702+R02872) first step of two-step reaction (R07652, R00702+R09793): This reaction is catalyzed by the presqualene diphosphate synthase (SSL-1) enzyme of the green alga TAX-869301. However, it is also a partial reaction catalyzed by two different enzymes - |FRAME:RXN-13162 "EC 2.5.1.21, squalene synthase"| and EC 2.5.1.96, 4,4'-diapophytoene synthase. The product, CPD-465, is only fromed by the presqualene diphosphate synthase of TAX-38881. In the other two cases, it is never released from the enzyme and is directly converted to the final product, squalene and 4,4'-diapophytoene, respectively.natural substrates
squalene synthase
2 (2E,6E)-farnesyl diphosphate = diphosphate + presqualene diphosphate
-
-
-
: first step of two-step reaction (R06223, R00702+R02872) first step of two-step reaction (R07652, R00702+R09793): This reaction is catalyzed by the presqualene diphosphate synthase (SSL-1) enzyme of the green alga TAX-869301. However, it is also a partial reaction catalyzed by two different enzymes - |FRAME:RXN-13162 "EC 2.5.1.21, squalene synthase"| and EC 2.5.1.96, 4,4'-diapophytoene synthase. The product, CPD-465, is only fromed by the presqualene diphosphate synthase of TAX-38881. In the other two cases, it is never released from the enzyme and is directly converted to the final product, squalene and 4,4'-diapophytoene, respectively.natural substrates
4,4'-diapophytoene synthase
2 (2E,6E)-farnesyl diphosphate = diphosphate + presqualene diphosphate
-
-
-
: first step of two-step reaction (R06223, R00702+R02872) first step of two-step reaction (R07652, R00702+R09793): This reaction is catalyzed by the presqualene diphosphate synthase (SSL-1) enzyme of the green alga TAX-869301. However, it is also a partial reaction catalyzed by two different enzymes - |FRAME:RXN-13162 "EC 2.5.1.21, squalene synthase"| and EC 2.5.1.96, 4,4'-diapophytoene synthase. The product, CPD-465, is only fromed by the presqualene diphosphate synthase of TAX-38881. In the other two cases, it is never released from the enzyme and is directly converted to the final product, squalene and 4,4'-diapophytoene, respectively.natural substrates
3beta-hydroxysteroid 3-dehydrogenase
4alpha-methylzymosterol + NADP+ = 3-dehydro-4-methylzymosterol + NADPH + H+
; "show the reaction diagram")
-
-
-
-
natural substrates
3beta-hydroxysteroid-4alpha-carboxylate 3-dehydrogenase (decarboxylating)
4alpha-carboxy-4beta-methyl-5alpha-cholesta-8,24-dien-3beta-ol + NADP+ = 3-dehydro-4-methylzymosterol + NADPH + CO2
; "show the reaction diagram")
-
-
-
-
natural substrates
DELTA14-sterol reductase
4,4-dimethyl-5alpha-cholesta-8,24-dien-3beta-ol + NADP+ = 4,4-dimethyl-5alpha-cholesta-8,14,24-trien-3beta-ol + NADPH + H+
; "show the reaction diagram")
-
-
-
: This enzyme acts on a range of steroids with a 14(15)-double bond.natural substrates
presqualene diphosphate + NADPH + H+ = squalene + diphosphate + NADP+
; "show the reaction diagram")
-
-
-
: second step of two-step reaction (R06223, R00702+R02872) following after R00702: This reaction is part of the overall reaction (see |FRAME:RXN-13162| catalyzed by squalene synthase which occurs in two steps: 1) |FRAME:RXN-12263| 2) presqualene diphosphate + NADPH = squalene + diphosphate + NADP (this reaction)natural substrates
presqualene diphosphate synthase
presqualene diphosphate + NADPH + H+ = squalene + diphosphate + NADP+
-
-
-
: second step of two-step reaction (R06223, R00702+R02872) following after R00702: This reaction is part of the overall reaction (see |FRAME:RXN-13162| catalyzed by squalene synthase which occurs in two steps: 1) |FRAME:RXN-12263| 2) presqualene diphosphate + NADPH = squalene + diphosphate + NADP (this reaction)natural substrates
squalene synthase
presqualene diphosphate + NADPH + H+ = squalene + diphosphate + NADP+
-
-
-
: second step of two-step reaction (R06223, R00702+R02872) following after R00702: This reaction is part of the overall reaction (see |FRAME:RXN-13162| catalyzed by squalene synthase which occurs in two steps: 1) |FRAME:RXN-12263| 2) presqualene diphosphate + NADPH = squalene + diphosphate + NADP (this reaction)natural substrates
Botryococcus squalene synthase
presqualene diphosphate + NADPH + H+ = squalene + diphosphate + NADP+
-
-
-
: second step of two-step reaction (R06223, R00702+R02872) following after R00702: This reaction is part of the overall reaction (see |FRAME:RXN-13162| catalyzed by squalene synthase which occurs in two steps: 1) |FRAME:RXN-12263| 2) presqualene diphosphate + NADPH = squalene + diphosphate + NADP (this reaction)natural substrates
botryococcene synthase
presqualene diphosphate + NADPH + H+ = squalene + diphosphate + NADP+
-
-
-
: second step of two-step reaction (R06223, R00702+R02872) following after R00702: This reaction is part of the overall reaction (see |FRAME:RXN-13162| catalyzed by squalene synthase which occurs in two steps: 1) |FRAME:RXN-12263| 2) presqualene diphosphate + NADPH = squalene + diphosphate + NADP (this reaction)natural substrates
squalene monooxygenase
squalene + [reduced NADPH-hemoprotein reductase] + O2 = (3S)-2,3-epoxy-2,3-dihydrosqualene + [oxidized NADPH-hemoprotein reductase] + H2O
; "show the reaction diagram")
-
-
-
-
natural substrates, generic, protein
squalene-hopene cyclase
(3S)-2,3-epoxy-2,3-dihydrosqualene = lanosterol
; "show the reaction diagram")
-
-
-
-
natural substrates
Lanosterol synthase
(3S)-2,3-epoxy-2,3-dihydrosqualene = lanosterol
-
-
-
-
natural substrates
sterol 14alpha-demethylase
lanosterol + [reduced NADPH-hemoprotein reductase] + O2 = 4,4-dimethyl-5alpha-cholesta-8,14,24-trien-3beta-ol + formate + [oxidized NADPH-hemoprotein reductase] + H2O
; "show the reaction diagram")
-
-
-
-
natural substrates, generic, protein
3beta-hydroxysteroid-4alpha-carboxylate 3-dehydrogenase (decarboxylating)
4alpha-carboxy-5alpha-cholesta-8,24-dien-3beta-ol + NADP+ = 5alpha-cholesta-8,24-dien-3-one + NADPH + CO2
; "show the reaction diagram")
-
-
-
-
natural substrates
DELTA7-sterol 5(6)-desaturase
5alpha-cholest-7-en-3beta-ol + 2 ferrocytochrome b5 + O2 + 2 H+ = cholesta-5,7-dien-3beta-ol + 2 ferricytochrome b5 + 2 H2O
; "show the reaction diagram")
-
-
-
-
natural substrates
7-dehydrocholesterol reductase
cholesterol + NADP+ = cholesta-5,7-dien-3beta-ol + NADPH + H+
; "show the reaction diagram")
-
-
-
-
natural substrates
3beta-hydroxysteroid 3-dehydrogenase
zymosterone + NADPH = zymosterol + NADP+
; "show the reaction diagram")
-
-
-
-
natural substrates
3(or 17)beta-hydroxysteroid dehydrogenase
zymosterone + NADPH = zymosterol + NADP+
-
-
-
-
natural substrates
17beta-estradiol 17-dehydrogenase
zymosterone + NADPH = zymosterol + NADP+
-
-
-
-
natural substrates
cholestenol DELTA-isomerase
5alpha-cholesta-8,24-dien-3beta-ol = 5alpha-cholesta-7,24-dien-3beta-ol
; "show the reaction diagram")
-
-
-
-
natural substrates
DELTA24-sterol reductase
5alpha-cholest-7-en-3beta-ol + NADP+ = 5alpha-cholesta-7,24-dien-3beta-ol + NADPH + H+
; "show the reaction diagram")
-
-
-
-
natural substrates
cholesterol 7-desaturase
cholesterol + O2 + NADPH + H+ = cholesta-5,7-dien-3beta-ol + NADP+ + 2 H2O
; "show the reaction diagram")
-
-
-
-
natural substrates