Taurine and hypotaurine are aminosulfinic acids. Taurine has many physiological functions as neuromodulators, membrane stabilizers, facilitator of ion transport and aiding auditory transduction. Hypotaurine has roles such as antioxidant and a protective agent. Taurine and hypotaurine are synthesized from L-cysteine. L-Cysteine is involved in cyanoacid metabolism and glutathione metabolism. L-Cysteine goes through redox reactions, elimination reactions and other metabolism pathways to eventually form taurine and hypotaurine. L-Cysteine is converted to cysteamine, which can then form hypotaurine through the enzyme cysteamine dioxygenase. L-Cysteine can also be converted to 3-sulfinoalanine through the enzyme cysteine dioxygenase. Hypotaurine can then be formed from the enzymes glutamate decarboxylase and sulfinoalanine decarboxylase acting on 3-sulfinoalanine. 3-sulfinoalanine can form taurine by first converting to L-cysteate. L-Cysteate is then metabolized to taurine via glutamate decarboxylase and sulfinoalanine decarboxylase. The hypotaurine formed in this pathway can be metabolised to taurine, then taurine is metabolised to 5-L-glutamyl-taurine by reacting with (5-L-glutamyl)-peptide via the enzyme gamma-glutamyltranspeptidase. Taurine can also undergo excretion from the organism.

Taurine & Hypotaurine Metabolism References