Tryptophan decarboxylase transamination

For two transaminases the remaining unknown stereochemical parameter was determined by demonstrating an internal transfer of tritium (dialkyl amino acid transaminase) [28] or deuterium (pyridoxamine-pyruvate transaminase) [27] from the a-position of the substrate L-alanine to C-4 of the cofactor. Internal hydrogen transfer from the a-position of the substrate amino acid to C-4 of PLP has also been demonstrated for two of the abortive transamination reactions, those catalyzed by tryptophan synthase fi2 protein [32] and by aspartate-/8-decarboxylase [31]. In addition, the same phenomenon must occur in alanine transaminase, as deduced from the observation that the enzyme catalyzes exchange of the /8-hydrogens of... 

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