Further Insights on the <i>Datura innoxia</i> Hyoscyamine 6<i>β</i>-Hydroxylase (DiH6H) Based on Biochemical Characterization and Molecular Modeling

Hyoscyamine, anisodamine and scopolamine are tropane alkaloids present in some Solanaceae species used modern medicine. L-Hyoscyamine is hydroxylated to 6β-hydroxyhyoscyamine (anisodamine) then epoxidated by the dual action of hyoscyamine 6β-hydroxylase (H6H), a 2-oxoglutarate dependent dioxygenase. A natural mutation Gly-220 residue Cys was previously shown be associated with loss function H6H Mandragora officinarum, preventing accumulation these plants. We show here that deliberate Gly220Cys Datura innoxia DiH6H protein caused both its enzymatic abilities rendered it unable hydroxylate L-hyoscyamine into epoxidate scopolamine. By using modeling based on an available crystal structure from metel, we how Cys220 causes steric interference active site cavity impairing interaction substrates, protein. also address enantiomeric preference molecular modeling.