Oxalate oxidoreductases () (OOR) are a relatively recently discovered group of enzymes that break down oxalate, a problematic molecule nutritionally. The first one to have been characterized has the systematic name oxalate:ferredoxin oxidoreductase. This enzyme catalyses the following chemical reaction:
The enzyme is known to contain thiamine diphosphate and [4Fe-4S] ironâÂÂsulfur clusters.
Another OOR from acetogenic bacteria, a thiamine pyrophosphate (TPP)-dependent OOR, had its mechanism of action decoded step by step under X-ray crystallography to rather simplistically (one-carbon) split oxalate, producing low-potential electrons and CO<sub>2</sub>.