Method of manufacturing a L- amino acid

The present invention is characterized in keto acid, in a reaction that converts the enzyme having the amino acid dehydrogenase and a coenzyme regeneration ability in L- amino acids by the action, to be added to the reaction by dividing the coenzyme more than once it is a method of manufacturing to L- amino acid. According to the method of the present invention, regardless of the purity of the keto acid is a substrate, by enzymatic reductive amination reaction, a high optical purity of L- amino acids are useful compounds as a synthetic intermediate for pharmaceutical products manufactured efficiently can do.