EC Number   |
Reaction |
Reference |
|---|
    1.1.1.42 | isocitrate + NADP+ = 2-oxoglutarate + CO2 + NADPH + H+ |
active site structure and reaction mechanism, conformational changes at the active site resulting in closed and open forms, regulatory residues are isocitrate-binding Asp279and Ser94 |
656233 |
| 1.1.1.42 | isocitrate + NADP+ = 2-oxoglutarate + CO2 + NADPH + H+ |
active site structure contains a well-ordered Mn2+-isocitrate complex, reaction mechanism |
656093 |
| 1.1.1.42 | isocitrate + NADP+ = 2-oxoglutarate + CO2 + NADPH + H+ |
overall reaction |
- |
| 1.1.1.42 | isocitrate + NADP+ = 2-oxoglutarate + CO2 + NADPH + H+ |
overall reaction, catalytic mechanism, overview. The catalysis proceeds in three steps: (1) NADP+ reduction by the isocitrate substrate with the help of the Lys212B base, (2) beta-decarboxylation of the resulting oxalosuccinate, generating an enolate, and (3) protonation of this intermediate by Tyr139A, giving rise to the 2-oxooglutarate product. The beta-decarboxylation of oxalosuccinate is the most likely rate-limiting step. Role of Mg2+ and Asp275A, whose acid/base properties throughout the catalytic cycle lower the barrier to physiologically competent values. The catalysis takes place in a closed-conformation quaternary complex and involves significant conformational changes as the divalent metal (Mg2+ or Mn2+), the NADP+ cofactor, and the trianionic form of the isocitrate substrate (ICT) sequentially bind |
739770 |
| 1.1.1.42 | isocitrate + NADP+ = 2-oxoglutarate + CO2 + NADPH + H+ |
protonation of the enolate to form product 2-oxoglutarate is the rate-limiting step |
-, 721687 |
| 1.1.1.42 | isocitrate + NADP+ = 2-oxoglutarate + CO2 + NADPH + H+ |
Ser95, Asn97, and Thr78 are important for the catalysis having distinguishable functions, overview |
657309 |
| 1.1.1.42 | isocitrate + NADP+ = 2-oxoglutarate + CO2 + NADPH + H+ |
Tyr140 and Lys212 are required for catalytic activity, Tyr140 is the general acid that protonates the substrate after decarboxylation, Lys212 lowers as a positively charged residue the pK of the nearby ionizable group in the enzyme-substrate complex and stabilizes the carbanion formed initially on substrate decarboxylation |
656180 |
| 1.1.1.42 | isocitrate + NADP+ = oxalosuccinate + NADPH + H+ |
(1a) |
- |
| 1.1.1.42 | oxalosuccinate = 2-oxoglutarate + CO2 |
(1b) |
- |
