title: Characterization of two heme oxygenase isoforms in rat spleen: comparison with the hematin-induced and constitutive isoforms of the liver.
abstract: Two isoforms of heme oxygenase, designated as HO-1 and HO-2, were identified in rat spleen. The most abundant form was HO-1, wherein a relative ratio of about 5:1 of HO-1 to HO-2 was detected. The splenic HO-1 and HO-2 were immunochemically similar to the purified isoforms obtained from the liver and the testis. Moreover, the elution properties of splenic HO-1 as well as those of the constitutive liver HO-1 and the hematin-induced liver HO-1 on a DEAE-sephacel column were similar. However, the splenic HO-1 activity could not be induced by hematin. It is suggested that in the spleen heme oxygenase activity is maintained in the induced state as the result of constant exposure to hemoglobin released in the course of disruption of senescent erythrocytes.
mesh_terms: D000818:Animals; D002852:Chromatography, Ion Exchange; D004790:Enzyme Induction / Q000187:drug effects; D006419:Heme Oxygenase (Decyclizing) / Q000276:immunology / Q000378:metabolism*; D006427:Hemin / Q000494:pharmacology; D005779:Immunodiffusion; D007527:Isoenzymes / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D051381:Rats; D013154:Spleen / Q000201:enzymology*
chemical_list: D007527:Isoenzymes; D006427:Hemin; D006899:Mixed Function Oxygenases; D006419:Heme Oxygenase (Decyclizing)