Sulfur Metabolism - Sulfur Use By Plants and Animals

Sulfur Use By Plants and Animals

Plants take up sulfate in their roots and reduce it to sulfide (see sulfur assimilation). Plants are able to reduce APS directly to sulfite (using APS reductase) without phosphorylating APS to PAPS. From the sulfide they form the amino acids cysteine and methionine, sulfur lipids, and other sulfur compounds. Animals obtain sulfur from cysteine and methionine in the protein that they consume. Sulfur is the third most abundant mineral element in the body. The amino acids cysteine and methionine are used by the body to make glutathione. Excess cysteine and methionine are oxidized to sulfate by sulfite oxidase, eliminated in the urine, or stored as glutathione (which can serve as a store for sulfur). The lack of sulfite oxidase, known as sulfite oxidase deficiency, causes physical deformities, mental retardation, and death.