. "Catalysis of the reaction: L-threonine = 2-oxobutanoate + NH3." . . "L-serine dehydratase activity" . "serine deaminase activity" . "L-threonine ammonia-lyase activity" . "L-threonine ammonia-lyase (2-oxobutanoate-forming)" . "L-threonine deaminase activity" . "L-threonine dehydratase activity" . "L-threonine hydro-lyase (deaminating) activity" . "threonine ammonia-lyase activity" . "threonine deaminase activity" . "threonine dehydrase activity" . "threonine dehydratase activity" . . .