Purification and some properties of the histidyl-tRNA synthetase from the cytosol of rabbit reticulocytes.
Purification and some properties of the histidyl-tRNA synthetase from the cytosol of rabbit reticulocytes.
复制标题
兔网织红细胞胞浆中组氨酰-tRNA 合成酶的纯化及其一些特性。
作者：
S. Kane;C. Vugrincić;D. Finbloom;D. W. Smith
兔网织红细胞胞浆的组氨酰-tRNA合成酶已被纯化84000倍至表观均一性，比活性为每分钟每毫克蛋白质形成687 nmol组氨酰-tRNA。10 - 15%的酶活性与核糖体一起沉积，而其余的则在胞质溶胶中。经蔗糖密度梯度离心法测得纯化酶的分子量为122000。在0.1%十二烷基硫酸钠存在下的凝胶电泳表明，它是由两个类似的亚基与分子量约64 000。该酶具有45 mM的镁最佳值;然而，在细胞内钾浓度（160 nM）的存在下，镁最佳值降低至5 mM。酶酰化兔网织红细胞的两个组氨酸tRNA isoceptor具有相似的Km值和相似的速率。
The histidyl-tRNA synthetase of rabbit reticulocyte cytosol has been purified 84 000-fold to apparent homogeneity with a specific activity of 687 nmol of histidyl-tRNA formed per min per mg of protein. Ten to 15% of the enzyme activity is sedimented with the ribosomes while the remainder is in the cytosol. The purified enzyme has a molecular weight of 122 000 as determined by sucrose density gradient centrifugation. Gel electrophoresis in the presence of 0.1% sodium dodecyl sulfate suggests that it is composed of two similar subunits with a molecular weight of approximately 64 000. The enzyme has a magnesium optimum of 45 mM; however, this is reduced to 5 mM in the presence of an intracellular potassium concentration (160 nM). The enzyme acylates the two histidine tRNA isoacceptors of rabbit reticulocytes with similar Km values and at similar rates.