Ting S J, Dunaway-Mariano D
FEBS Lett. 1984 Jan 9;165(2):251-3. doi: 10.1016/0014-5793(84)80179-9.
The substrate activities of a series of tripositive metal ion-pyrophosphate complexes with yeast inorganic pyrophosphatase were examined. While the Michaelis constants for these complexes were shown to be between one and two orders of magnitude greater than that of the natural substrate, [Mg(H2O)4PPi]2-, the turnover numbers were in general comparable to that of [Mg(H2O)4PPi]2-. These data suggest that the nature of the metal ion cofactor effects substrate binding but in most cases not catalysis. Thus, the role of the metal ion in catalysis is probably restricted to that of an electron sink.
研究了一系列三价金属离子-焦磷酸配合物与酵母无机焦磷酸酶的底物活性。虽然这些配合物的米氏常数比天然底物[Mg(H₂O)₄PPi]²⁻的米氏常数大1至2个数量级，但转换数总体上与[Mg(H₂O)₄PPi]²⁻的转换数相当。这些数据表明，金属离子辅因子的性质影响底物结合，但在大多数情况下不影响催化作用。因此，金属离子在催化中的作用可能仅限于作为一个电子受体。
