van der Ouderaa F J, Buytenhek M, Slikkerveer F J, van Dorp D A
Biochim Biophys Acta. 1979 Jan 29;572(1):29-42. doi: 10.1016/0005-2760(79)90197-8.
Prostaglandin endoperoxide synthetase is a membrane-bound glycoprotein isolated as a dimer of molecular weight of approximately 129 000 consisting of two identical polypeptide chains. Several research workers have reported that haemin (ferri-protoporphyrin-IX) is required to restore the full enzymic activity of the pure apoprotein. Difference spectroscopy shows association of haemin up to two molecules per polypeptide chain of molecular weight 70 000. Both the cyclooxygenase and the peroxidase activity displayed by the enzyme can be optimally stimulated by similar quantities of haemin. The restored haemin-enzyme complex has a millimolar absorption coefficient at 408 nm of 61 mM-1 . cm-1 per haem. Using this value, the presence of non-haem iron in the enzyme is virtually excluded. These findings and the spectra of the reassociated enzyme-haemin complex point to a haemoprotein character. The availability of haemin to the enzyme might play a regulating rôle in its action.
前列腺素内过氧化物合成酶是一种膜结合糖蛋白，分离得到的二聚体分子量约为129000，由两条相同的多肽链组成。几位研究人员报告说，血红素（铁原卟啉-IX）是恢复纯脱辅基蛋白的全部酶活性所必需的。差示光谱显示，每70000分子量的多肽链最多可结合两个血红素分子。该酶所显示的环氧化酶和过氧化物酶活性都可被相似量的血红素最佳地刺激。恢复后的血红素-酶复合物在408nm处的毫摩尔吸收系数为每血红素61mM-1·cm-1。利用该值，实际上排除了酶中存在非血红素铁的可能性。这些发现以及重新结合的酶-血红素复合物的光谱表明其具有血红蛋白的特性。血红素对该酶的可及性可能在其作用中发挥调节作用。
