4-alpha-hydroxytetrahydrobiopterin dehydratase activity https://github.com/geneontology/go-ontology/issues/30193 pterin-4-alpha-carbinolamine dehydratase activity RHEA:11920 EC:4.2.1.96 KEGG_REACTION:R04734 tetrahydrobiopterin dehydratase activity 4-alpha-hydroxy-tetrahydropterin dehydratase activity Reactome:R-HSA-71146 4a-hydroxytetrahydrobiopterin dehydratase activity molecular_function 4a-hydroxytetrahydrobiopterin hydro-lyase activity pterin-4alpha-carbinolamine dehydratase activity 4alpha-hydroxy-tetrahydropterin dehydratase activity GO:0008124 Catalysis of the 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. MetaCyc:RXN-7908 (6R)-6-(L-erythro-1,2-dihydroxypropyl)-5,6,7,8-tetrahydro-4a-hydroxypterin hydro-lyase [(6R)-6-(L-erythro-1,2-dihydroxypropyl)-7,8-dihydro-6H-pterin-forming] pterin-4a-carbinolamine dehydratase activity hydro-lyase activity