In the Tripeptide Glutathione (γ-Glutamyl-Cysteinyl-Glycine), the Side Chain Carboxyl Group

Multiple Choice

In the tripeptide glutathione (γ-glutamyl-cysteinyl-glycine) , the side chain carboxyl group of glutamate forms a peptide bond with the α-amino group of cysteine.The α-amino and α-carboxyl groups of glutamate do not participate in peptide bonds.Approximately what is the isoelectric point (pK) of glutathione?

A) 1.5.
B) 10.0.
C) 3.0.
D) 6.5.
E) 9.0.