title: Deficient 5 alpha-reductase due to mutant enzyme with reduced affinity to steroid substrate.
abstract: Enzyme kinetics of 5 alpha-reductase were compared in cultured genital skin fibroblasts taken from 6 control subjects and from an affected subject with 5 alpha-reductase deficiency in whom the diagnosis was established on hormonal grounds. The Km value for testosterone in the mutant enzyme was extremely high (1,427 vs. 185-417 nmol/l in controls). in the mutant enzyme was extremely high (1,427 vs 185-417 nmol/l in controls). A A mutant but stable enzyme with reduced affinity to steroid substrate is reported.
mesh_terms: D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000172:deficiency* / Q000378:metabolism; D013734:Androgen-Insensitivity Syndrome / Q000201:enzymology; D002478:Cells, Cultured; D002675:Child, Preschool; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D012734:Disorders of Sex Development / Q000201:enzymology* / Q000235:genetics; D004963:Estrenes / Q000378:metabolism*; D005260:Female; D005347:Fibroblasts / Q000201:enzymology; D005835:Genitalia / Q000201:enzymology; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D015741:Metribolone; D010088:Oxidoreductases / Q000172:deficiency*; D013739:Testosterone / Q000097:blood
chemical_list: D006063:Chorionic Gonadotropin; D004963:Estrenes; D015741:Metribolone; D013739:Testosterone; D010088:Oxidoreductases; D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase