Guanidinoethyl sulfonate, also known as taurocyamine, is a natural guanidine-taurine analog derived from taurine. It is an intermediate of taurine and hypotaurine metabolism and is phosphorylated by taurocyamine kinase. Guanidinoethyl sulfonate competitively inhibits taurine uptake by sodium-dependent taurine transporters in rat hepatocytes (Ki = 1.75 mM). It also acts as a competitive glycine receptor antagonist in mouse striatal neurons. Plasma levels of guanidinoethyl sulfonate are significantly increased in patients with chronic renal failure.
A potent inhibitor of taurine transport.
ChEBI: Zwitterionic form of taurocyamine arising from transfer of a proton from the sulfo to the guanidino group; major species at pH 7.3.
guanidinoethyl sulphonate was found to be an analogue of taurine and an inhibitor of taurine transport. guanidinoethyl sulphonate was also shown to be a weak agonist at gaba(a) receptors, and was able to antagonize gaba-evoked responses. guanidinoethyl sulphonate did not gate glyr. 3. but antagonized glycine responses in a concentration-dependent and surmountable manner. glycine receptor-mediated taurine responses were competitively antagonized by guanidinoethyl sulphonate. taurine dose-response curves, in contrast to the glycine dose-response curves were shifted by guanidinoethyl sulphonate to the right in a parallel manner [1].
guanidinoethyl sulphonate delivered in the drinking water of rats for 1 month could effectively reduce taurine levels in brain structures and outside the brain by between 50 and 80 %, depending on the tissue. this partial taurine depletion could not affect either basal synaptic transmission or the late phase of long-term potentiation in hippocampal slices. in-vivo microdialysis studies in the hippocampus demonstrated that guanidinoethyl sulphonate was able to reduce extracellular taurine levels and the magnitude of taurine released in response to the application of either n-methyl-d-aspartate or a hypoosmotic solution [2].
[1] sergeeva, o. a.,chepkova, a.n., and hass, h.l. guanidinoethyl sulphonate is a glycine receptor antagonist in striatum. british journal of pharmacology 137, 855-860 (2002).
[2] suárez lm, muoz md, gonzález jc, bustamante j, del río rm, solís jm. the taurine transporter substrate guanidinoethyl sulfonate mimics the action of taurine on long-term synaptic potentiation. amino acids. 2016 nov;48(11):2647-2656. epub 2016 jul 15.
