Sall I, Metais P, Ferard G
Enzyme. 1977;22(3):158-65. doi: 10.1159/000458784.
Subcellular fraction (brush border, mitochondria, microsomes and plasma membranes) are isolated from the rat intestinal epithelial cells. A comparison was made between the effect of cold storage, freeze-thawing, heating and of some chemicals (DMSO, DTT, glycerol, sucrose) on the stability of Mg2+ and (Na+-K+) dependent ATPases in these fractions in order to determine possible difference linked to the localization in the enterocyte. Enzymatic activities were found more stable at -20 degrees C than at +4 degrees C. Microsomal (Na+-K+)-ATPase increased in activity until the 8th day, then declined. Brush border (Na+-K+)-ATPase was the least resistant of all fractions. For Mg2+-ATPase, that from mitochondria was that had lost much more activity (84%) in 15 days at +4 degrees C. With freeze-thawing there was a comparable decrease in all activities (20-35%). by heating between 35 and 60 degrees C, Mg2+-ATPase was shown to be more heat resistant than (Na+-K+)-ATPase. The addition of some stabilizing chemicals (DMSO, glycerol, sucrose) improved the heat stability of the two enzymes: better results were obtained with glycerol for Mg2+-ATPase and sucrose for (Na+-K+)-ATPase. These differences might be due to the compositon in membraine lipids or to the nature of the enzymes studied.
从大鼠肠上皮细胞中分离出亚细胞组分（刷状缘、线粒体、微粒体和质膜）。比较了冷藏、冻融、加热以及某些化学物质（二甲基亚砜、二硫苏糖醇、甘油、蔗糖）对这些组分中Mg2+和（Na+-K+）依赖性ATP酶稳定性的影响，以确定与肠细胞中定位相关的可能差异。发现酶活性在-20℃比在+4℃时更稳定。微粒体（Na+-K+）-ATP酶的活性在第8天之前增加，然后下降。刷状缘（Na+-K+）-ATP酶是所有组分中抗性最低的。对于Mg2+-ATP酶，线粒体中的Mg2+-ATP酶在+4℃下15天内活性损失更多（84%）。冻融后所有活性都有类似程度的下降（20%-35%）。在35至60℃之间加热时，Mg2+-ATP酶比（Na+-K+）-ATP酶更耐热。添加一些稳定化化学物质（二甲基亚砜、甘油、蔗糖）可提高两种酶的热稳定性：对于Mg2+-ATP酶，甘油效果更好；对于（Na+-K+）-ATP酶，蔗糖效果更好。这些差异可能归因于膜脂组成或所研究酶的性质。
