Mitochondrial aconitase A swivel domain. Aconitase (also known as aconitate hydratase and citrate hydro-lyase) catalyzes the reversible isomerization of citrate and isocitrate as part of the TCA cycle. This is the aconitase swivel domain, which undergoes swivelling conformational change in the enzyme mechanism. In eukaryotes two isozymes of aconitase are known to exist: one found in the mitochondrial matrix and the other found in the cytoplasm. This is the mitochondrial form. The mitochondrial product is coded by a nuclear gene. Most members of this subfamily are mitochondrial but there are some bacterial members.