Threonine deaminase: a novel activity stain on polyacrylamide gels.

With phenazine methosulfate and nitro blue tetrazolium, an activity stain for threonine deaminase has been developed. Because the deamination reaction does not involve any overall oxidation or reduction, it is proposed that one of the intermediates of the reaction, alpha-aminocrotonate or alpha-iminobutyrate, is the reducing agent. Studies with ferricyanide as the artificial electron acceptor indicate that a decarboxylation of the intermediate occurs during the dye reduction.