Taniguchi K, Suzuki K, Iida S
J Biol Chem. 1983 Jun 10;258(11):6927-31.
The addition of ATP to (Na+,K+)-ATPase (EC 3.6.1.3) of pig kidney modified with N-[p-(2-benzimidazolyl)phenyl]maleimide induced three different modes of fluorescence change: positive, biphasic, and negative, which were observed, respectively, in the presence of Mg2+ with 16 or 160, 320 or 640, and 1500 mM Na+. At 16-320 mM Na+, the extent of positive change was almost saturated at 0.4 microM ATP, but the rate of the change was significantly accelerated by much higher concentrations of ATP. In the presence of 640 mM Na+, the change showed an initial small decrease in fluorescence (t 1/2 = 15 ms), followed by an increase (t 1/2 = 145 ms). The amount of phosphoenzyme increased rapidly and gave a steady level (t 1/2 = 38 ms) after the addition of ATP to give 12.2 microM. Comparison of the relative fluorescence intensity and the amount of phosphoenzyme at a given time permitted modeling the amount of ADP-sensitive phosphoenzyme and K+-sensitive phosphoenzyme present. A simulation gave a good fit to the smoothed data. These data show directly that ATP is hydrolyzed through ADP-sensitive phosphoenzyme and K+-sensitive phosphoenzyme in the presence of Mg2+ and Na+.
用N-[对-(2-苯并咪唑基)苯基]马来酰亚胺修饰猪肾的(Na +,K +)-ATP酶（EC 3.6.1.3）后添加ATP，会诱导三种不同模式的荧光变化：正向、双相和负向，分别在存在Mg2+且Na+浓度为16或160、320或640以及1500 mM的情况下观察到。在16 - 320 mM Na+时，0.4 microM ATP时正向变化程度几乎达到饱和，但更高浓度的ATP会显著加速变化速率。在640 mM Na+存在下，变化显示荧光最初有小幅下降（t 1/2 = 15毫秒）随后上升（t 1/2 = 145毫秒）。添加ATP至12.2 microM后，磷酸化酶的量迅速增加并达到稳定水平（t 1/2 = 38毫秒）。比较给定时间的相对荧光强度和磷酸化酶的量，可以对存在的ADP敏感磷酸化酶和K+敏感磷酸化酶的量进行建模。模拟结果与平滑后的数据拟合良好。这些数据直接表明，在Mg2+和Na+存在下，ATP通过ADP敏感磷酸化酶和K+敏感磷酸化酶水解。
