4a-hydroxytetrahydrobiopterin dehydratase

In enzymology, a 4a-hydroxytetrahydrobiopterin dehydratase is an enzyme that catalyzes the chemical reaction


 * (6R)-6-(L-erythro-1,2-dihydroxypropyl)-5,6,7,8-tetrahydro-4a- hydroxypterin $$\rightleftharpoons$$ (6R)-6-(L-erythro-1,2-dihydroxypropyl)-7,8-dihydro-6H-pterin + H2O

Thus, the two substrates of this enzyme are (6R)-6-(L-erythro-1,2-dihydroxypropyl)-5,6,7,8-tetrahydro-4a- and hydroxypterin, whereas its two products are (6R)-6-(L-erythro-1,2-dihydroxypropyl)-7,8-dihydro-6H-pterin and H2O.

This enzyme belongs to the family of lyases, specifically the hydro-lyases, which cleave carbon-oxygen bonds. The systematic name of this enzyme class is (6R)-6-(L-erythro-1,2-dihydroxypropyl)-5,6,7,8-tetrahydro-4a-hydroxy pterin hydro-lyase [(6R)-6-(L-erythro-1,2-dihydroxypropyl)-7,8-dihydro-6H-pterin-formin g]. Other names in common use include 4alpha-hydroxy-tetrahydropterin dehydratase, pterin-4alpha-carbinolamine dehydratase, and 4a-hydroxytetrahydrobiopterin hydro-lyase.

Structural studies
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes, , and.