L-threonine + L-serine => L-threonyl-L-serine + H2O
l-threonine + l-serine => l-threonyl-l-serine + h2o
L-threonine + L-serine => L-threonyl-L-serine + H2O
l-threonine + l-serine => l-threonyl-l-serine + h2o