▁of ▁is omer ases , ▁specifically ▁those ▁intr am ole cular ▁ox id ored uct ases ▁trans pos ing ▁C = C ▁b onds . ▁ ▁The ▁system atic ▁name ▁of ▁this ▁en zym e ▁class ▁is ▁ 3 - ox ost ero id ▁ Δ 5 - Δ 4 - is omer ase . ▁Other ▁names ▁in ▁common ▁use ▁include ▁k et ost ero id ▁is omer ase ▁( K SI ), ▁hydro x yst ero id ▁is omer ase , ▁ster oid ▁is omer ase , ▁ Δ 5 - ket ost ero id ▁is omer ase , ▁ Δ 5 ( or ▁ Δ 4 )- 3 - ket o ▁ster oid ▁is omer ase , ▁ Δ 5 - st ero id ▁is omer ase , ▁ 3 - ox ost ero id ▁is omer ase , ▁ Δ 5 - 3 - ket o ▁ster oid ▁is omer ase , ▁and ▁ Δ 5 - 3 - ox ost ero id ▁is omer ase . ▁ ▁K SI ▁has ▁been ▁studied ▁extens ively ▁from ▁the ▁b acter ia ▁Com am onas ▁test oster oni ▁( TI ), ▁formerly ▁referred ▁to ▁as ▁Pseud omon as ▁test oster oni , ▁and ▁Pseud omon as ▁put ida ▁( PI ). ▁The ▁en zym es ▁from ▁these ▁two ▁sources ▁are ▁ 3 4 % ▁hom olog ous , ▁and ▁struct ural ▁studies ▁have ▁shown ▁that ▁the ▁pla cement ▁of ▁the ▁catal yt ic ▁groups ▁in ▁the ▁active ▁sites ▁is ▁virt ually ▁identical