1.11.2.5 H191A mutant loses ability to hydroxylate 3-methyl-L-tyrosine -, 725507 1.11.2.5 H274A mutant loses ability to hydroxylate 3-methyl-L-tyrosine -, 725507 1.11.2.5 H313A mutant loses ability to hydroxylate 3-methyl-L-tyrosine. Heme content of the mutant enzyme is very low, very little heme-Fe binding ability -, 725507 1.11.2.5 H317A mutant loses ability to hydroxylate 3-methyl-L-tyrosine. Heme content of the mutant enzyme is very low, very little heme-Fe binding ability -, 725507