Baker J O
Methods Enzymol. 1988;158:33-55. doi: 10.1016/0076-6879(88)58046-1.
The design of a metal ion buffer system useful in a given enzymological application is subject to a number of different requirements. 1. The total concentration of added metal ion, Mt, should be large enough to damp out the effect of any adventitious quantities of the same metal ion and to overwhelm adventitious quantities of other metal ions. 2. The ratio of free to bound ligand should be high enough that the calculated ratio between the concentrations of free metal ion M and Mt will not be unduly sensitive to uncertainties in the values of metal-ligand stability constants. If possible, [Lt]/[Mt] should be large enough that the variation of free metal ion concentration, [M], with [Mt] will be effectively linear in the range of interest. 3. The concentrations of metal ion buffer species, both the free ligand and metal-ligand complexes, should be kept reasonably low in order to minimize the possibility of perturbation of the enzyme/metal ion equilibrium. The best design will be that which most successfully balances these sometimes opposing requirements.
在特定酶学应用中有用的金属离子缓冲系统的设计需要满足许多不同的要求。1. 添加的金属离子的总浓度Mt应足够大，以消除任何偶然存在的相同金属离子的影响，并抑制其他金属离子的偶然存在量。2. 游离配体与结合配体的比例应足够高，以使计算出的游离金属离子M和Mt浓度之间的比例对金属-配体稳定常数数值的不确定性不过于敏感。如果可能的话，[Lt]/[Mt]应足够大，以使游离金属离子浓度[M]随[Mt]的变化在感兴趣的范围内有效地呈线性。3. 金属离子缓冲物种的浓度，即游离配体和金属-配体络合物的浓度，应保持在合理的低水平，以尽量减少干扰酶/金属离子平衡的可能性。最佳设计将是最成功地平衡这些有时相互矛盾的要求的设计。
