title: Soluble and microsomal forms of NADH-cytochrome beta 5 reductase from human placenta. Similarity with NADH-methemoglobin reductase from human erythrocytes.
abstract: In congenital methemoglobinemia associated with mental retardation a generalized deficiency of NADH-cytochrome beta 5 reductase (NADH : ferricytochrome beta 5 oxidoreductase, EC 1.6.2.2) has been found in soluble extracts of red blood cells, as well as in deoxycholate-treated extracts of leukocytes, muscle, liver and fibroblasts (Leroux et al. (1975) Nature 258, 619-620). In the present study the relationship between the microsomal (I) and the soluble (II) NADH-cytochrome beta 5 reductase was investigated, using human placenta as a source of enzyme. Both forms were compared to the human red-cell soluble NADH-methemoglobin reductase (III) and NADH-cytochrome beta 5 reductase (IV). The four entities exhibited great immunological similarities. It is concluded that the three soluble enzymes (II, III and IV) are identical. The detergent-solubilized microsomal NADH-cytochrome beta 5 reductase (I) is immunologically very similar to the soluble enzymes, but presents distinct features possibly due to the presence of a hydrophobic part.
mesh_terms: D003579:Cytochrome Reductases / Q000032:analysis* / Q000276:immunology / Q000302:isolation & purification; D042966:Cytochrome-B(5) Reductase / Q000032:analysis* / Q000276:immunology / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes / Q000201:enzymology*; D005260:Female; D006801:Humans; D007118:Immunoassay; D005779:Immunodiffusion; D007526:Isoelectric Point; D008861:Microsomes / Q000201:enzymology; D008970:Molecular Weight; D009247:NADH, NADPH Oxidoreductases / Q000032:analysis*; D010920:Placenta / Q000201:enzymology*
chemical_list: D009247:NADH, NADPH Oxidoreductases; D003579:Cytochrome Reductases; D042966:Cytochrome-B(5) Reductase