Biosynthesis of L-2,3-diaminopropanoic acid

Abstract

The biosynthesis of L-2,3-diaminopropanoic acid (L-DAP) was studied by means of incorporation of ²H-labelled precursors into the simple microbial metabolite N²-L-alanyl-N³-fumaramoyl-L-2,3-diaminopropanoic acid (2). By ²H n.m.r. spectroscopic analysis, it was established that L-serine is the biosynthetic precursor of L-DAP via a process in which the α-hydrogen of serine is eliminated, both β-hydrogens are retained, and ammonia is bound to C_β with retention of configuration. These findings are in accord with the mechanism of pyridoxal phosphate-dependent β-replacement reactions of serine which proceed by transient generation of an aminoacrylate intermediate and addition of a nucleophile to the double bond with retention of configuration.