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