New roles for cysteine and transsulfuration enzymes: production of H2S, a neuromodulator and smooth muscle relaxant.
The enzymes of the transsulfuration pathway also have the capacity to catalyze the desulfhydration of cysteine. Recent studies demonstrate a role of the transsulfuration enzymes, cystathionine gamma-lyase and cystathionine beta-synthase, in catalyzing the desulfhydration of cysteine in brain and smooth muscle. The H2S produced from cysteine functions as a neuromodulator and smooth muscle relaxant. In glutamatergic neurons, the production of H2S by cystathionine beta-synthase enhances N-methyl-D-aspartate (NMDA) receptor-mediated currents. In smooth muscle cells, H2S produced by cystathionine gamma-lyase enhances the outward flux of potassium by opening potassium channels, leading to hyperpolarization of membrane potential and smooth muscle relaxation.
Dominy
John E
JE
Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA.
Stipanuk
Martha H
MH
D000818:Animals; D001921:Brain / Q000378:metabolism; D003541:Cystathionine beta-Synthase / Q000378:metabolism; D003542:Cystathionine gamma-Lyase / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism*; D006801:Humans; D006862:Hydrogen Sulfide / Q000378:metabolism*; D009126:Muscle Relaxation / Q000502:physiology*; D009130:Muscle, Smooth / Q000502:physiology*
D003541:Cystathionine beta-Synthase; D003542:Cystathionine gamma-Lyase; D003545:Cysteine; D006862:Hydrogen Sulfide