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血红素氧合酶(HO)是血红素代谢中的重要限速酶。人类编码HO基因大约14Kb,由5个外显子及4个内含子组成。HO的长度为288个氨基酸残基。从基因核苷酸序列,已经推断出HO蛋白的一级结构和二级结构。HO的二级结构由α—螺旋(45%),β—片层(18%),旋转(12%)和任意卷曲残基组成。活性中心位于富含组氨酸区的132～172区城。血红素、一些激素、细菌内毒素等是其诱导剂,而大多数金属卟啉类化合物是其抑制剂。金属卟啉是一类与天热血红素IX相似的化合物,锡—金属卟啉最具代表性。它与HO结合,作用机制可能为:抑制HO的活性;取代白蛋白位点上联结的胆红素;增加肝对胆红素的摄取及分泌;增加胆红素的肠—肝循环;增加胆红素的光破坏作用。目前已成功地用于治疗ABO溶血病,胆汁性肝硬化和特发性血色病。唯一的副作用为—过性光过敏现象。在治疗黄疸方面具有广阔前景。
Heme oxygenase (HO) is an important rate-limiting enzyme in heme metabolism. Human coding HO gene about 14Kb, by five exons and four introns. The length of HO is 288 amino acid residues. From the gene nucleotide sequence, the primary structure and the secondary structure of the HO protein have been deduced. The secondary structure of HO consists of α-helix (45%), β-sheet (18%), rotation (12%) and any curly residue. Active center is located in the area of histidine rich 132 ~ 172 district. Heme, some hormones, bacterial endotoxins and the like are their inducers, while most metalloporphyrins are their inhibitors. Metalloporphyrins are a class of compounds similar to Thermohalogen IX, the most representative of which is tin-metalloporphyrin. It binds to HO and may have the following mechanisms: inhibition of HO activity; replacement of conjugated bilirubin at the albumin site; increased uptake and secretion of bilirubin by the liver; increased intestinal-hepatic circulation of bilirubin; Light destruction of the role of the red. Has been successfully used to treat ABO hemolytic disease, biliary cirrhosis and idiopathic hemochromatosis. The only side effect is the phenomenon of transient hypersensitivity. In the treatment of jaundice has broad prospects.