Sulfate/Sulfite Metabolism

This pathway illustrates the conversion of sulfite to sulfate (via sulfate oxidase) and subsequent generation of adenylylsulfate (APS) via 3’-phosphoadenosine 5’-phosphosulfate synthase 2. APS is converted to phosphoadenylyl-sulfate (PAPS) via adenylylsulfate kinase. APS can also be regenerated from PAPS by 3’(2’), 5’-bisphosphate nucleotidase 1. PAPS is eventually converted to adenosine bisophosphate (PAP) through the action of several different enzymes including aryl sulfotransferase, chondroitin 4-sulfotransferase 13 and estrone sulfotransferase. Sulfites are defined as compounds that contain the sulfite ion SO2−. The sulfite ion is the conjugate base of sulfurous acid. Sulfites occur naturally in all wines. Sulfites are commonly introduced to arrest fermentation at a desired time, and may also be added to wine as preservatives to prevent spoilage and oxidation at several stages of winemaking. Sulfites are also used as preservatives in dried fruits, and dried potato products.

References

1. Lehninger, A.L. (2005) Lehninger principles of biochemistry (4 ^th ed.). New York: W.H Freeman.
2. Salway, J.G. (2004) Metabolism at a glance (3 ^rd ed.). Alden, Mass. : Blackwell Pub.