4a-hydroxytetrahydrobiopterin Dehydratase

In enzymology, a 4a-hydroxytetrahydrobiopterin dehydratase (EC 4.2.1.96) is an enzyme that catalyzes the chemical reaction

(6R)-6-(L-erythro-1,2-dihydroxypropyl)-5,6,7,8-tetrahydro-4a- hydroxypterin (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 . Other names in common use include 4alpha-hydroxy-tetrahydropterin dehydratase, pterin-4alpha-carbinolamine dehydratase, and 4a-hydroxytetrahydrobiopterin hydro-lyase.