Heme is an essential cofactor for innumerable hemoproteins among which the most important are hemoglobin in the red blood cells and microsomal/mitochondrial cytochromes, which are used in redox and respiratory reactions in all cells, mainly in the hepatocytes. The heme synthesis occurs in all cells, starting from Glycine and Succinyl-CoA, and passes through eight enzymatic reactions, of which four occur in the cytoplasm, and the remaining four occur in the mitochondria. Detects associated with these enzymes result in Porphyria, a group of rare inherited metabolic disorders. Moreover, increasing evidence suggests that free heme exerts vasculo-toxic and pro-inflammatory effects causing endothelial dysfunction, oxidative stress and inflammation by activating endothelial and immune cells. Hemolysis, transfusions and ineffective erythropoiesis contribute to heme overload with scavenger depletion and toxic ‘free’ species formation. Finally disturbed heme metabolism has been related to mitochondrial decay and metabolic changes seen in ageing and age-related disorders.
Heme is an essential cofactor for innumerable hemoproteins among which the most important are hemoglobin in the red blood cells and microsomal/mitochondrial cytochromes, which are used in redox and respiratory reactions in all cells, mainly in the hepatocytes. The heme synthesis occurs in all cells, starting from Glycine and Succinyl-CoA, and passes through eight enzymatic reactions, of which four occur in the cytoplasm, and the remaining four occur in the mitochondria. Detects associated with these enzymes result in Porphyria, a group of rare inherited metabolic disorders. Moreover, increasing evidence suggests that free heme exerts vasculo-toxic and pro-inflammatory effects causing endothelial dysfunction, oxidative stress and inflammation by activating endothelial and immune cells. Hemolysis, transfusions and ineffective erythropoiesis contribute to heme overload with scavenger depletion and toxic ‘free’ species formation. Finally disturbed heme metabolism has been related to mitochondrial decay and metabolic changes seen in ageing and age-related disorders.