Aminolevulinate dehydratase (δ-ALA-D) as marker protein of intoxication with metals and other pro-oxidant situations

delta-ALA-D is a metalloenzyme that has 3 vicinal thiol/thiolate groups that coordinate with Zn(II). The proximity between the sulfhydryl groups renders delta-ALA-D extremely sensitive to oxidation by soft electrophiles, such as Pb(II), Hg(II), As(III) and organoseleno and organotellurium compounds. In fact, blood delta-ALA-D is a classical biomarker of lead exposure in humans. The inhibition of delta-ALA-D can increase the concentration of 5-aminolevulinate (delta-ALA), which is a pro-oxidant compound. delta-ALA can generate oxidative stress that can further increase delta-ALA-D inhibition. Recently, data have been obtained indicating that the delta-ALA-D could be a marker of oxidative stress in human pathologies. In summary, considering its high sensitivity to pro-oxidant situations, delta-ALA-D can be considered a universal marker of oxidative stress.