Problem 91 - Chemistry: The Central Science

Question

Glutathione is a tripeptide found in most living cells. Partial hydrolysis yields Cys-Gly and Glu-Cys. What structures are possible for glutathione?

Step-by-Step Solution

Answer

The possible structure for glutathione based on the given information is \( Glu - Cys - Gly \).

Step 1: Identify the amino acids present in the dipeptides

From the given information, we have two dipeptides: Cys-Gly and Glu-Cys. The amino acids present in these dipeptides are Cys (Cysteine), Gly (Glycine), and Glu (Glutamic acid).

Step 2: Understand the link between dipeptides and tripeptide

Since glutathione is a tripeptide, it must be composed of three amino acids connected by peptide bonds. We have two dipeptides Cys-Gly and Glu-Cys, with Cys being common between them. This indicates that Cys must be one of the central amino acids in the sequence in order for the other two amino acids (Gly and Glu) to connect and form a tripeptide.

Step 3: Determine the possible structure for glutathione

Since Cys is the central amino acid in the sequence, we need to connect the other two amino acids (Gly and Glu) to Cys in the structure of glutathione. There can be one possible arrangement for the tripeptide: Glu-Cys-Gly. So, the possible structure for glutathione based on the given information is \( Glu - Cys - Gly \).