preferred_name: S-sulfanyl-L-cysteine + 2-aminoprop-2-enoate => L-cystine
preferred_name_lc: s-sulfanyl-l-cysteine + 2-aminoprop-2-enoate => l-cystine
label: S-sulfanyl-L-cysteine + 2-aminoprop-2-enoate => L-cystine
label_lc: s-sulfanyl-l-cysteine + 2-aminoprop-2-enoate => l-cystine