A 35-year-old woman presents with dry, brittle hair and frequent skin infections. She has a history of mild intellectual disability. Laboratory tests reveal low serum copper levels, and genetic testing confirms a mutation in the ATP7A gene, consistent with Menkes disease. The physician explains that copper is required for enzymes that stabilize protein structure, including those involved in disulfide bond formation. Which of the following interactions is most responsible for maintaining the stability of tertiary protein structure in extracellular proteins like keratin and antibodies?
