Chemoenzymatic synthesis of 1-deaza-pyridoxal 5′-phosphate

Formation of aspartate aminotransferase internal aldimine with 1-deaza-pyridoxal 5´-phosphate. The free cofactor analogue, λ max ∼350 nm, displays a bathochromic shift upon formation of the internal aldimine, λ max ∼420 nm. The internal aldimine with pyridoxal 5´-phosphate absorbs at ∼430 nm. The first synthesis of 1-deaza-pyridoxal 5′-phosphate (2-formyl-3-hydroxy-4-methylbenzyl phosphate) is described. The chemoenzymatic approach described here is a reliable route to this important isosteric pyridoxal phosphate analogue. This work enables elucidation of the role of the pyridine nitrogen in pyridoxal 5′-phosphate dependent enzymes.