This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Classification and metabolism of amino acids, Subject name: Biochemistry
[{'content': 'Adenosine receptor stability is because of extensive disulfide bonds formed between: \nSelect and explain. \nA. Cysteine, B. Methionine, C. Arginine, D. Alanine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Disulfide bonds can only be formed between one amino acid i.e. cysteine, as it has sulfhydryl group (-SH). Two cysteine gets joined to form cystine (having disulfide bond) (see fig). It a strong covalent bond.', 'role': 'assistant'}]