Enzymatic synthesis of N -formylated sialosides via a five-enzyme cascade.

Here we report an enzymatic approach to synthesize N -formylneuraminic acid (Neu5Fo) containing sialosides, through a five-enzyme cascade. This method stands as an alternative to traditional chemical syntheses, aiming for precision and efficiency in generating sialosides with a tailored N -formyl group generated directly from formic acid. The newly synthesized Neu5Fo was characterized using various NMR techniques revealing a conformational equilibrium at the amide bond of the formyl group in slow exchange on the NMR time scale with a trans  :  cis ratio of ∼2 : 1. This work not only suggests potential for exploring the biological roles of sialosides but also points to the possibility of developing novel therapeutic agents.