Glutathione (GSH) is a tripeptide that serves as a mild reducing agent to detoxify peroxides and maintain the cysteineresidues of hemoglobin and other red blood cell proteins in the reduced state. Complete hydrolysis of glutathione givesGly, Glu, and Cys. Treatment of glutathione with carboxypeptidase gives glycine as the first free amino acid released.Treatment of glutathione with 2,4-dinitrofluorobenzene (Sanger reagent, Problem 24-21, page 1246), followed bycomplete hydrolysis, gives the 2,4-dinitrophenyl derivative of glutamic acid. Treatment of glutathione with phenylisothiocyanate does not give a recognizable phenylthiohydantoin, however.(a) Propose a structure for glutathione consistent with this information. Why would glutathione fail to give a normalproduct from Edman degradation, even though it gives a normal product from the Sanger reagent followed byhydrolysis?(b) Oxidation of glutathione forms glutathione disulfide (GSSG). Propose a structure for glutathione disulfide, and writea balanced equation for the reaction of glutathione with hydrogen peroxide.
Glutathione (GSH) is a tripeptide that serves as a mild reducing agent to detoxify peroxides and maintain the cysteine
residues of hemoglobin and other red blood cell proteins in the reduced state. Complete hydrolysis of glutathione gives
Gly, Glu, and Cys. Treatment of glutathione with carboxypeptidase gives glycine as the first free amino acid released.
Treatment of glutathione with 2,4-dinitrofluorobenzene (Sanger reagent, Problem 24-21, page 1246), followed by
complete hydrolysis, gives the 2,4-dinitrophenyl derivative of glutamic acid. Treatment of glutathione with phenyl
isothiocyanate does not give a recognizable phenylthiohydantoin, however.
(a) Propose a structure for glutathione consistent with this information. Why would glutathione fail to give a normal
product from Edman degradation, even though it gives a normal product from the Sanger reagent followed by
hydrolysis?
(b) Oxidation of glutathione forms glutathione disulfide (GSSG). Propose a structure for glutathione disulfide, and write
a balanced equation for the reaction of glutathione with hydrogen peroxide.
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