NADP+-dependent isocitrate dehydrogenase (IDH)

To the left is shown the 3D structure of NADP-dependent isocitrate dehydrogenase IDH from Escherichia coli, complexed with isocitrate dehydrogenase and Mg2+.

Isocitrate dehydrogenase is one of the enzymes involved in the Kreb's cycle. It catalyses the oxidation of isocitrate to alpha-ketoglutarate, with NADP acting as a coenzyme (in the case of E.coli -- eukaryotes have a NAD dependent form of the enzyme as well). The reaction is facilitated by a divalent metallic cofactor (Mg2+, Mn2+, etc.)
SRS entry for IDH

Secondary structure
     Color coding is as follows:
      Helix - magenta
      Beta sheet - yellow
      Turn -blue
      Other - white

      With H-bonds

 Show Mg2+ (metallic cofactor)

 Show isocitrate (substrate)

 Show phosphorylation site (Serine 113)
      Phosphorylation at this site is used to regulate the activity of E.coli IDH. (Pubmed)

 Show isocitrate and isopropylmalate
     dehydrogenase family signature
     (residues 303-322, Prosite)

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