Hechtenberg S, Beyersmann D
Institut für Zellbiologie, Biochemie und Biotechnologie, Universität Bremen, BRD.
Enzyme. 1991;45(3):109-15. doi: 10.1159/000468875.
The effect of Cd2+, Pb2+ and Hg2+ on the Ca(2+)-ATPase activity of sarcoplasmic reticulum from rabbit muscle was studied. The concentration of relevant free and complex species for the assay conditions have been computed. As a result, ATP hydrolysis was found to be inhibited with an IC50 value of 950 nmol/l free Cd2+ or 95 nmol/l free Pb2+. Although calculation of the free Hg2+ was not possible, the comparison of the IC50 values for total metal ions show that Hg2+ is the strongest inhibitor of enzyme activity. The inhibition by Cd2+ seems to be independent of substrate concentration, whereas the inhibitory effect of Pb2+ is lowered in the presence of higher MgATP concentrations. Our data illustrate that the three heavy metals are potent inhibitors of the Ca2+ pump. Therefore low concentrations of these metal ions may disturb intracellular Ca2+ homeostasis and act on Ca(2+)-mediated cell functions.
研究了Cd2+、Pb2+和Hg2+对兔肌肉肌浆网Ca(2+)-ATP酶活性的影响。已计算出测定条件下相关游离和络合物物种的浓度。结果发现，ATP水解受到抑制，游离Cd2+的IC50值为950 nmol/l，游离Pb2+的IC50值为95 nmol/l。虽然无法计算游离Hg2+，但总金属离子IC50值的比较表明，Hg2+是酶活性最强的抑制剂。Cd2+的抑制作用似乎与底物浓度无关，而在较高MgATP浓度存在时，Pb2+的抑制作用会降低。我们的数据表明，这三种重金属都是Ca2+泵的有效抑制剂。因此，低浓度的这些金属离子可能会扰乱细胞内Ca2+稳态，并作用于Ca(2+)介导的细胞功能。
