Question

The most common covalent cross-links in proteins are sulfur-sulfur bonds that form

between two amino acids with -SH (thiol) groups as side chains. Which amino acid has
this side chain?

Answer 1

Cysteine is the amino acid with a thiol side chain that forms disulfide bonds, contributing to the stability and tertiary structure of proteins.

Step-by-step explanation:

The amino acid that has a -SH (thiol) side chain and forms disulfide linkages in proteins through an oxidation reaction is cysteine. When two cysteine amino acids come into proximity within a protein, their thiol groups can undergo oxidation, which results in the formation of a disulfide bond (R-S-S-R).

This type of bond is significant as it contributes to the protein's tertiary structure by providing stability and can be formed intramolecularly or intermolecularly.