preferred_name: 2-aminobut-2-enoate + L-cysteine => L,L-cystathionine
preferred_name_lc: 2-aminobut-2-enoate + l-cysteine => l,l-cystathionine
label: 2-aminobut-2-enoate + L-cysteine => L,L-cystathionine
label_lc: 2-aminobut-2-enoate + l-cysteine => l,l-cystathionine