Dailey H A
Department of Microbiology, University of Georgia, Athens 30602.
Ann N Y Acad Sci. 1987;514:81-6. doi: 10.1111/j.1749-6632.1987.tb48763.x.
Ferrochelatase activity was examined both in growing MEL cells and in in vitro assays of the purified enzyme to determine what effect a variety of divalent cations would have. Data obtained with the purified enzyme demonstrated that Mn2+ strongly inhibits the activity in a competitive fashion with respect to Fe2+ with a calculated Ki of 15 microM. Cadmium ion is also inhibitory (Ki: 50 microM), as is Hg2+ and arsenite, but Pb2+ is a poor inhibitor. All other metals tested had no effect. When these same metal ions were tested on differentiating MEL cells it was found that their ability to inhibit both heme formation and ferrochelatase activity mimicked their in vitro effect on purified ferrochelatase.
在生长的MEL细胞以及纯化酶的体外试验中检测了亚铁螯合酶活性，以确定各种二价阳离子会产生何种影响。用纯化酶获得的数据表明，Mn2+以与Fe2+竞争的方式强烈抑制活性，计算得出的Ki为15微摩尔。镉离子也具有抑制作用（Ki：50微摩尔），Hg2+和亚砷酸盐同样如此，但Pb2+的抑制作用较弱。所测试的所有其他金属均无影响。当在分化的MEL细胞上测试这些相同的金属离子时，发现它们抑制血红素形成和亚铁螯合酶活性的能力与其在体外对纯化亚铁螯合酶的作用相似。
