research papers
The first X-ray analysis of porphobilinogen deaminase from a plant reveals an extensive highly conserved loop region covering the active site that was completely disordered in previous structures. Structural comparisons suggest that the concerted movements of two enzyme domains may be linked to elongation of the substrate and that during the elongation cycle the bound dipyrromethane cofactor or polypyrrole intermediate moves to vacate one of the cofactor subsites such that an incoming pyrrole moiety can bind.