(S)-2-ethyl-2-hydroxy-3-oxobutanoate + thiamine diphosphate => 2-(1-hydroxyethyl)thiamine diphosphate + 2-oxobutanoate
(s)-2-ethyl-2-hydroxy-3-oxobutanoate + thiamine diphosphate => 2-(1-hydroxyethyl)thiamine diphosphate + 2-oxobutanoate