Michell A R, Lindheimer M D, Katz A I
Enzyme. 1977;22(5):341-7. doi: 10.1159/000458815.
The in vitro optimum pH of renal (Na+, K+)-ATPase, assumed to be 7.8, depends on the type of ATP used. The accepted value is obtained with 'grade II' ATP but with purer ATP ('Sigma grade') it lies close to the intracellular pH in rat medulla and cortex (pH 7.0, 7.2). Values were identical in rats subjected to dietary potassium depletion for 2-4 weeks. The optimal Mg2+ concentration was also influenced by the type of ATP but Mg ATPase activity was unaffected. Both types of ATP were hydrolysed by trichloracetic acid. Where the purer ATP is used the assay conditions need to be modified accordingly.
肾（钠+，钾+）-ATP酶的体外最适pH值假定为7.8，这取决于所使用的ATP类型。公认的值是使用“二级”ATP获得的，但使用纯度更高的ATP（“西格玛级”）时，其值接近大鼠髓质和皮质中的细胞内pH值（pH 7.0、7.2）。在经历2至4周饮食性钾缺乏的大鼠中，这些值是相同的。最佳镁离子浓度也受ATP类型的影响，但镁ATP酶活性不受影响。两种类型的ATP都可被三氯乙酸水解。当使用纯度更高的ATP时，测定条件需要相应修改。
