Ito K, Minamiura N, Yamamoto T
J Biochem. 1984 May;95(5):1399-406. doi: 10.1093/oxfordjournals.jbchem.a134747.
DNase I in human urine was purified to an electrophoretically homogeneous state by column chromatographies on DEAE-lignocellulose, hydroxyapatite, DEAE-cellulose, Sephadex G-75 and elastin-celite. The purified enzyme was immunologically identical with human pancreatic DNase I, but not with bovine pancreatic DNase I. The molecular weight and isoelectric point of the enzyme were estimated to be 4.1 X 10(4) and 3.6, respectively. The amino acid analysis revealed that 1 mol of the enzyme contained 8 mol of half-cystine. The N-terminal amino acid was identified as leucine by the dansyl chloride method. The enzyme was active in the presence of Mg2+, Co2+, or Mn2+, The optimum pH was around 6.5. The enzyme was stable in the pH range from 5.0 to 9.0 and at temperatures lower than 45 degrees C. The rate of hydrolysis of native DNA by the enzyme was twice as fast as that observed with heat-denatured DNA. This enzyme exhaustively degraded about 20% of the phosphodiester bonds in native DNA. The enzyme also degraded poly(dA) and poly(dT), but hardly degraded poly(dG) and poly(dC).
通过在DEAE-木质纤维素、羟基磷灰石、DEAE-纤维素、葡聚糖凝胶G-75和弹性蛋白-硅藻土上进行柱色谱，将人尿中的脱氧核糖核酸酶I（DNase I）纯化至电泳纯状态。纯化后的酶在免疫学上与人胰腺DNase I相同，但与牛胰腺DNase I不同。该酶的分子量和等电点估计分别为4.1×10⁴和3.6。氨基酸分析表明，1摩尔该酶含有8摩尔半胱氨酸。通过丹磺酰氯法确定其N端氨基酸为亮氨酸。该酶在Mg²⁺、Co²⁺或Mn²⁺存在时具有活性，最适pH约为6.5。该酶在pH 5.0至9.0范围内以及温度低于45℃时稳定。该酶对天然DNA的水解速率是热变性DNA的两倍。这种酶能彻底降解天然DNA中约20%的磷酸二酯键。该酶还能降解聚（dA）和聚（dT），但几乎不降解聚（dG）和聚（dC）。
