Role of Cysteine in Protein Stability

In the human body, amino acids serve as the building blocks of proteins, each contributing to the diverse functions of biomolecules. One amino acid, known for its unique side chain, is cysteine, which contains a thiol (-SH) group. This functional group plays a significant role in the formation of disulfide bonds, which are vital for stabilizing the tertiary and quaternary structures of proteins.

Consider the following statement: "Cysteine, due to its ability to form disulfide bonds, is essential for maintaining the structure of proteins in environments such as extracellular spaces where oxidative conditions prevail." Based on this, which of the following statements regarding the characteristics and properties of cysteine is TRUE?