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 Cβ 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.