Sulfur is reduced or oxidized in many organisms - its metabolism often yields either energy (e.g. dissimilatory sulfur reduction in some bacteria) or organo-sulfur compounds (via assimilatory sulfate reduction), such as glutathione. In the common fruit fly, sulfur metabolism is typically assimilatory. The enzyme that converts elemental sulfur to sulfide (akin to the Claus equilibrium) is not yet characterized, but methanethiol (methyl mercaptan), an organic form of sulfur, is converted to sulfide in a reaction catalysed by methanethiol oxidoreductase. The first step of sulfide metabolism, a reaction catalysed by an oxidoreductase in the mitochondrial matrix, involves the acceptance of the sulfane sulfur via glutathione (or sulfite) and the entry of electrons into the electron transport chain via FAD and quinones. Another oxidoreductase converts S-sulfanyl glutathione into sulfite. Sulfotransferases can relay and convert thiosulfates into sulfites for metabolism. Sulfite is then converted into sulfate, which then feeds into selenocompund and nucleoside metabolism via PAPS synthetases.

Sulfur Metabolism References