10 year old boy presented with abdominal pain, muscle weakness and fatigue. On investigations, serum lead levels were found increased in blood. Activity of which of following enzyme in the liver is increased

High levels of lead can affect heme metabolism by combining with SH groups in enzymes such as Ferrochelatase and ALA dehydratase (Zinc containing enzyme). This affect porphyrin metabolism. Elevated levels of protoporphyrin are found in red blood cells and elevated levels of ALA and coporphyrin are found in urine. Accumulation of ALA is a result of inhibition of ALA-D and over activity of ALA synthase which leads to the given symptoms.