Catalyzes the cleavage of L-allo-threonine and L-threonine to glycine and acetaldehyde. L-threo-phenylserine and L-erythro-phenylserine are also good substrates. L-threonine = acetaldehyde + glycine L-allo-threonine = acetaldehyde + glycine Optimum pH is 8.5-9.0. Optimum temperature is 65-70 degrees Celsius. Homotetramer. Belongs to the threonine aldolase family.