EC Number   |
Reaction |
Reference |
|---|
   5.4.99.17 | squalene + H2O = hopan-22-ol |
- |
- |
| 5.4.99.17 | squalene = hop-22(29)-ene |
- |
- |
| 5.4.99.17 | squalene = hop-22(29)-ene |
catalytic mechanism via Friedel-Crafts alkylation and substrate specificity, overview |
-, 728821 |
| 5.4.99.17 | squalene = hop-22(29)-ene |
catalytic mechanism, overview |
727345 |
| 5.4.99.17 | squalene = hop-22(29)-ene |
catalytic mechanism, the initial reaction catalyzed is the protonation of the terminal double bond of squalene. The conserved DXDD motif of SHCs is essential for this protonation reaction, overview |
726715 |
| 5.4.99.17 | squalene = hop-22(29)-ene |
catalytic mechanism, the initial reaction catalyzed is the protonation of the terminal double bond of squalene. The conserved DXDD motif of SHCs is essential for this protonation reaction. In Alicyclobacillus acidocaldarius SHC, Asp376 of this motif is hydrogen bonded to His451, and an additional hydrogen bond exists to an ordered water molecule, which connects D376 to the hydroxyl group of the Y495 side chain and thus further enhances its acidity. The carboxyl groups of Asp374 and Asp377 accommodate the positive charge of the D376-H451 pair prior to proton transfer. After proton transfer to the 2,3-double bond of squalene, the D376-H451 pair loses its charge, leaving the remaining negative charge on the D374-D377 pair for stabilization of the initial cationic intermediates (24, 101). Reprotonation of D376 occurs through a water molecule bound to Y495-OH, which can transfer protons from disordered water in the solvent-accessible upper cavity of SHC |
726715 |
| 5.4.99.17 | squalene = hop-22(29)-ene |
overall mechanism of the polycyclization reaction of SHCs and structures of squalene cyclization products, overview |
726715 |
