Mechanism of alpha-oxoamine synthases: identification of the intermediate Claisen product in the 8-amino-7-oxononanoate synthase reaction.

The reactive beta-ketoacid pyridoxal-5'-phosphate aldimine formed in the condensation step of the 8-amino-7-oxononanoate synthase reaction was 'trapped' in the enzyme-bound form by carrying out the reaction with l-alanine methyl ester and pimeloyl-CoA affording the more stable methyl ester of the putative intermediate, the characterisation of which provides the first definitive evidence for a beta-ketoacid intermediate in an alpha-oxamine synthase mechanism.