| Abstrakt: |
Levorotatory mono- and diiodotyrosine (MIT, DIT) are deiodinated when administered to normal man by mouth or intravenously (Foster & Gutman, 1930; Stanbury et al., 1956; Stanbury & Litvak, 1957). The deiodination is accomplished by a microsomal enzyme which is present in thyroid, liver, and kidney, and requires reduced triphosphopyridine nucleotide as a cofactor (Querido et al., 1956; Stanbury, 1957). The enzyme follows simple kinetics in vitro and has a dissociation constant of the order of 10−7M (Stanbury, 1957, Stanbury & Morris, 1958). The capacity of animal tissues in vitroor of man to metabolize the dextrorotatory isomers of MIT and DIT has not been reported before, except as inferred from studies with racemic mixtures in man (Stanbury et al., 1956).A number of patients have recently been reported who have familial cretinism and goiter and who have in common a lack of tissue deiodinase. Thus, they represent a |
