It employs one cofactor, thiamin diphosphate (TPP), and plays a key role in catabolism of oxalate, a highly toxic compound that is a product of the oxidation of carbohydrates in many bacteria and plants.

[1] Oxalyl-CoA decarboxylase is extremely important for the elimination of ingested oxalates found in human foodstuffs like coffee, tea, and chocolate,[2] and the ingestion of such foods in the absence of Oxalobacter formigenes in the gut can result in kidney disease or even death as a result of oxalate poisoning.

[3] Oxalyl-CoA decarboxylase is hypothesized to be evolutionarily related to acetolactate synthase, a TPP-dependent enzyme responsible for the biosynthesis of branched chain amino acids in certain organisms.

[9][10] A key feature of the cofactor TPP is the relatively acidic proton bound to the carbon atom between the nitrogen and sulfur in the thiazole ring, which has a pKa near 10.

[13] The thiamine diphosphate-binding site rests on the subunit-subunit interface between two of the domains, which is commonly seen in its class of enzymes.