Adenosine receptor stability is because of extensive disulfide bonds formed between:
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.
Cysteine
Methionine
Arginine
Alanine
Classification and metabolism of amino acids