摘要:
The nonenzymatic cyclic dimerisation of 5-aminolevulinic acid (5-ALA) leads to the formation of a pyrazine (3) and, under some circumstances, pseudo-porphobilinogen (1). On the other hand, the enzyme-catalysed process leads to porphobilinogen (PBG). The products of the former reaction were identified from their NMR spectra and mechanisms for their formation are proposed.