Gbenle G O
Department of Biochemistry, College of Medicine, University of Lagos, Nigeria.
Exp Parasitol. 1990 Nov;71(4):432-8. doi: 10.1016/0014-4894(90)90069-o.
T. brucei cytoplasmic calcium-dependent alkaline ribonuclease activity from DEAE-cellulose fractionation was separated into endoribonuclease and exoribonuclease activities by hydroxyapatite chromatography. T. brucei cytoplasmic extract markedly decreased the endoribonuclease activity, but slightly potentiated the activities of the exoribonuclease and bovine ribonuclease A. While the endoribonuclease was activated by trypsin, the exoribonuclease and bovine ribonuclease A were partially inactivated by trypsin. The endoribonuclease was activated by p-chloromercuribenzoate or N-ethylmaleimide; the exoribonuclease was not affected by these sulfhydryl group reagents. Free ribonuclease was separated from the latent endoribonuclease by 1 M NaCl-Sephadex G-100 gel filtration. The results demonstrate that T. brucei cytoplasm contains a latent endoribonuclease consisting of ribonuclease and inhibitor protein.
通过羟基磷灰石色谱法，将从DEAE-纤维素分级分离得到的布氏锥虫细胞质钙依赖性碱性核糖核酸酶活性分离为内切核糖核酸酶和外切核糖核酸酶活性。布氏锥虫细胞质提取物显著降低了内切核糖核酸酶活性，但略微增强了外切核糖核酸酶和牛核糖核酸酶A的活性。虽然内切核糖核酸酶被胰蛋白酶激活，但外切核糖核酸酶和牛核糖核酸酶A被胰蛋白酶部分失活。内切核糖核酸酶被对氯汞苯甲酸或N-乙基马来酰亚胺激活；外切核糖核酸酶不受这些巯基试剂的影响。通过1M NaCl-葡聚糖凝胶G-100凝胶过滤将游离核糖核酸酶与潜在的内切核糖核酸酶分离。结果表明，布氏锥虫细胞质含有一种由核糖核酸酶和抑制蛋白组成的潜在内切核糖核酸酶。
