2-oxobutanoate + L-cysteine + NH4(+) => L,L-cystathionine + H2O
2-oxobutanoate + l-cysteine + nh4(+) => l,l-cystathionine + h2o
2-oxobutanoate + L-cysteine + NH4(+) => L,L-cystathionine + H2O
2-oxobutanoate + l-cysteine + nh4(+) => l,l-cystathionine + h2o