3D Structure of IDH from
E. coli

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This is the structure of an IDH monomer from E. coli. The large extention to the right side interacts with the other subunit to form a homodimer.

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First, let's see the substrate, isocitrate. It is shown in a ball and stick display with CPK colors.

Zoom in on isocitrate.

Now let's look at the coenzyme, NADP⁺. It is shown in a ball and stick display with CPK colors; isocitrate is too.

Zoom in on NADP⁺. Isocitrate is below the much larger NADP ⁺ .

Finally, let's see where the cofactor Mg²⁺ (green sphere) is located. NADP⁺ and isocitrate remain unchanged in appearance.

Zoom in on Mg²⁺.
Notice that Mg²⁺ is very close to isocitrate.

There are two water molecules that help position the Mg²⁺ in the right place to peform its function.

Let's see what all of these look like in with their Van der Waals radii displayed. See how closely isocitrate , NADP⁺ and Mg²⁺