COMPARED RECOGNITION OF DISULFIDE AND TRISULFIDE SUBSTRATES BY GLUTATHIONE AND TRYPANOTHIONE REDUCTASES

Trypanothione trisulfide was synthesized according to two strategies. It was found to be recognized and reduced by trypanothione reductase a s the natural disulfide substrate. At the difference with the mechanis m observed for the reduction of glutathione trisulfide by glutathione reductase, the intermediate trypanothione persulfide was rapidly reduc ed. The enzymatic reduction of another trisulfide derived from an alte rnative substrate of trypanothione reductase was also studied. The str ucture of the trisulfide bridge of the substrate (intra- or intermolec ular) appeared to be a determining factor in the enzymatic reduction p attern. Moreover, in the case of the alternative substrate of trypanot hione reductase, differences of kinetics appeared for the first time b etween a di- and a trisulfide species. All kinetic parameters are give n.