Hydroxymethyl bilane is a major anabolic product, from the biosynthetic reaction of porphobilinogen ( PBG ) and uroporphyrinogen I synthase ( known as porphobilinogen deaminase ).
22.
An example of such a conformational disease is ALAD porphyria, which results from a mutation of porphobilinogen synthase that causes a shift in its morpheein equilibrium.
23.
This intermediate is then attacked by the dipyrrole cofactor of porphobilinogen deaminase, which after losing a proton yields a trimer covalently bound to the enzyme ( 2 ).
24.
A number of substances interfere with the Ehrlich reaction on the Multistix strip : porphobilinogen, indican, p-amino salicylic acid, sulphonamide, methyldopa, procaine and chlorpromazine.
25.
After various failed attempts to diagnose Mark, House tests Marks urine for porphobilinogen; the test turns out positive, and Mark is diagnosed with acute intermittent porphyria ( AIP ).
26.
It is an autosomal recessive disorder that results from inappropriately low levels of the enzyme ALA dehydratase ( ALAD, also called porphobilinogen synthase ), which is required for normal heme synthesis.
27.
A dipyrrole, a cofactor of this enzyme consisting of two condensed porphobilinogen molecules, is covalently attached to domain 3 and extends into the active site, the cleft between domains 1 and 2.
28.
Many studies suggest that mammalian PAH shows behavior comparable to porphobilinogen synthase ( PBGS ), wherein a variety of factors such as pH and ligand binding are reported to affect enzyme activity and protein stability.
29.
This lone-pair effect becomes dramatic for zinc-binding proteins, such as the above-mentioned porphobilinogen synthase, as the natural substrate cannot bind anymore-in those cases the protein is inhibited.
30.
Several positively charged arginine residues, positioned to face the active site from domains 1 and 2, have been shown to stabilize the carboxylate functionalities on the incoming porphobilinogen as well as the growing pyrrole chain.
