preferred_name: L-homocysteine + L-serine => L,L-cystathionine + H2O
preferred_name_lc: l-homocysteine + l-serine => l,l-cystathionine + h2o
label: L-homocysteine + L-serine => L,L-cystathionine + H2O
label_lc: l-homocysteine + l-serine => l,l-cystathionine + h2o