title: Metabolism of 5-S-glutathionyldopa.
abstract: 5-S-Glutathionyldopa is oxidized at incubation with tyrosinase and dopa producing a black pigment. The reaction proceeds with the formation of two chromophores with absorption spectra similar to those of dopachrome and melanochrome, respectively. Zn2+ catalyses the formation of the melanochrome-like compound. The oxidation of 5-S-glutathionyldopa by dopaquinone, formed by the action of human tyrosinase and mushroom tyrosinase, is considerably slower than that of 5-S-cysteinyldopa. The higher oxidation potential of 5-S-glutathionyldopa, and/or the greater number of dopaquinone molecules necessary for pigment formation from 5-S-glutathionyldopa and/or the formation of tyrosinase-inhibiting products from 5-S-glutathionyldopa can explain the slower oxidation of this compound. The oxidative pathways suggested for 5-S-glutathionyldopa by the present findings may be relevant both in the melanocyte and in non-specific oxidation of cathechols occurring in other cells.
mesh_terms: D001487:Basidiomycota / Q000201:enzymology; D002460:Cell Line; D002570:Ceruloplasmin / Q000378:metabolism; D003548:Cysteinyldopa / Q000031:analogs & derivatives / Q000378:metabolism*; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000378:metabolism; D006801:Humans; D006892:Hydroxydopamines / Q000378:metabolism; D066298:In Vitro Techniques; D008545:Melanoma / Q000201:enzymology; D014442:Monophenol Monooxygenase / Q000378:metabolism; D010084:Oxidation-Reduction; D013053:Spectrophotometry
chemical_list: D006892:Hydroxydopamines; C027802:5-hydroxydopamine; D003548:Cysteinyldopa; C033574:glutathionyldopa; D004295:Dihydroxyphenylalanine; D014442:Monophenol Monooxygenase; D002570:Ceruloplasmin