The canonical monomeric form of IMPDH has a molecular mass of approximately 55 kDa[4] and generally consists of 400-500 residues.

[5][11] Monovalent cations have been shown to activate most IMPDH enzymes and may serve to stabilize the conformation of the active-site loop.

[13][14][15][16] Other deletion examples of the Bateman domain in IMPDH have shown an enhanced in vitro catalytic activity in comparison with the corresponding wild-type counterpart.

[18][19] IMPDH has also been shown to bind nucleic acids,[20][21] and this function can be impaired by mutations that are located in the Bateman domain.

[24] Drosophila IMPDH has been demonstrated to act as a sequence-specific transcriptional repressor that can reduce the expression of histone genes and E2F.

NADH dissociates from the enzyme and a mobile active-site flap element moves a conserved catalytic dyad of arginine and threonine into the newly unoccupied NAD binding site.

The arginine residue is thought to act as the general base that activates a water molecule for the hydrolysis reaction.