Stereochemistry of formation of the hydroxymethyl group of hydroxymethylbilane, the precursor of uro'gen-III
Abstract
A new synthetic route to (11S)- and (11R)-[11-3H1]porphobilinogen (PBG) is described and the configurations of the products are assigned by degradation to (2S)- and (2R)-[2-3H1]glycollic acids; these PBG samples are used to establish that hydroxymethylbilane synthase converts PBG into the hydroxymethylbilane with overall retention of configuration at the HOCH2– group.