Sulfur-containing amino acids: a neurochemical perspective

This review charts recent developments in understanding the neurochemistry of endogenous sulfur-containing amino acids as neuromodulators, metabolic intermediates and potential toxins. The amino acids discussed include L-cysteine, L-cysteine sulfinic acid, L-cysteic acid, L-homocysteine, L-homocysteine sulfinic acid, L-homocysteic acid and taurine. Particular emphasis is placed on examining the mechanism and regulation of biochemical pathways that contribute to the synthesis and metabolism of cysteine, especially in its capacity as precursor of glutathione, taurine and hydrogen sulfide. Evidence concerning the role of cysteine and its oxidised form, cystine, in the control of intracellular and extracellular redox potentials and in the response of cells to oxidative stress is presented. Lastly, the therapeutic potential of intervention in the pathways of sulfur-containing amino acid metabolism in the brain is discussed.