Sulfite Oxidase

From Proteopedia

Image:Chicken-sulfite-oxidase-500w.jpg --Kimberly Meyers 23:21, 14 April 2009 (IDT)

Sulfite oxidase is a crucial enzyme that is responsible for oxidizing harmful sulfites to sulfates. The enzyme is found in the mitochondria of the cell and mostly can be found in hearts, kidneys and livers. Very little can be seen in the brain, skeletal muscle, blood and spleen.

The enzyme is a homodimer, a chemical entity consisting of two identical subunits called monomers, which are linked together by intramolecular forces. Sulfite oxidase contains two identical subunits. Each subunit has two domains, iron and molybdenum that are linked together by a loop composed of amino acids.

The molybdopertin cofactor is crucial to the enzyme because the oxidation of the sulfite occurs at the molybdenum center; the molybdenum center serves as the active site.

The molybdopertin cofactor is crucial to the enzyme because the oxidation of the sulfite occurs at the molybdenum center; the molybdenum center serves as the active site. When the molybdenum reacts with sulfite (Figure 1). One oxygen atom is transferred to sulfite, which produces sulfate and consequently reduces the molybdenum center by two electrons, thus resulting in Mo(IV). Intramolcular electron transfer from Mo(IV) to Fe(III) results in Fe(II) and Mo(V). One-electron photochemical reduction then moves Fe(II) to the exterior cytochrome resulting in Fe(III). This process occurs twice, and restores the enzyme to its original state. Image:Sulfite Oxidase electron transfer image.jpg

Point mutations in sulfite oxidase and defects in the molybdenum cofactor synthesis can ultimately lead to sulfite oxidase deficiency. The disorder causes neurological disorders, mental retardation, physical deformities, deterioration of the brain, and ultimately death.