Malke H, Gerlach D, Köhler W, Ferretti J J
Mol Gen Genet. 1984;196(2):360-3. doi: 10.1007/BF00328072.
Using recombinant DNA techniques, we introduced a previously cloned streptokinase gene from Streptococcus equisimilis into the Challis strain of S. sanguis (group H). The gene was expressed in the new host under the control of its own promoter and the gene product had biological properties identical to authentic streptokinase. However, the molecular weight of cloned streptokinase (42 K) as expressed by S. sanguis was substantially lower than that of authentic streptokinase (47 K). Since the cloned streptokinase gene encoded a 47 K mature protein, the lowered molecular weight of S. sanguis streptokinase may reflect posttranslational proteolytic cleavage, which leaves the biological activity of the gene product and its serological reactivity unimpaired.
利用重组DNA技术，我们将先前从类马链球菌克隆的链激酶基因导入血链球菌（H组）的Challis菌株中。该基因在其自身启动子的控制下在新宿主中表达，基因产物具有与天然链激酶相同的生物学特性。然而，血链球菌表达的克隆链激酶的分子量（42K）明显低于天然链激酶（47K）。由于克隆的链激酶基因编码一种47K的成熟蛋白，血链球菌链激酶分子量的降低可能反映了翻译后蛋白水解切割，这并不损害基因产物的生物学活性及其血清学反应性。
