4.2.1.96	4a-hydroxytetrahydrobiopterin = 6,7-dihydrobiopterin + H2O	-	-	
4.2.1.96	4a-hydroxytetrahydrobiopterin = 6,7-dihydrobiopterin + H2O	His61 and His79 act as acid catalysts for the stereospecific elimination of the 4a(R)- and 4a(S)-hydroxyl groups, respectively. The role of His62 is primarily binding substrate with additional component of base catalysis	5940	
4.2.1.96	4a-hydroxytetrahydrobiopterin = 6,7-dihydrobiopterin + H2O	mechanism	5929	
4.2.1.96	4a-hydroxytetrahydrobiopterin = 6,7-dihydrobiopterin + H2O	the mechanism of dehydration involves base catalysis at the N(5)-H group of the substrate by His61	5933