Kumagai H, Igarashi K, Yoshikawa M, Hirose S
J Biochem. 1977 Feb;81(2):381-8. doi: 10.1093/oxfordjournals.jbchem.a131469.
The effects of polyamines on the breakdown of synthetic polynucleotides [poly(A), poly(C), and poly(U)] by E. coli ribonuclease I [ribonucleate 3'-oligonucleotidohydrolase, EC 3.1.4.23] and ribonuclease II [EC 3.1.4.1] have been studied. The degradation of poly(C) by RNase II was stimulated by spermine and spermidine, while that of poly(A) by RNase II was not affected by polyamines. Under our standard experimental conditions, the breakdown of poly(U) by RNase II was inhibited slightly by polyamines. The stimulatory effect of spermine and spermidine on the breakdown of poly(C) occurred in the absence of monovalent cations but not in the absence of divalent cations. When polyamines were used as a stimulant of RNase II, the ratio of poly(C) degradation to poly(U) degradation was greater in the presence of inhibitors such as poly(G) than in their absence. Although the breakdown of all synthetic polynucleotides by RNase I was stimulated by polyamines, the degree of stimulation by polyamines was in the order poly(C)greater than poly(A)(see text)poly(U). However, the difference in degree of stimulation among polynucleotides decreased as monovalent cation concentration was increased.
研究了多胺对大肠杆菌核糖核酸酶I[核糖核酸3'-寡核苷酸水解酶，EC 3.1.4.23]和核糖核酸酶II[EC 3.1.4.1]催化合成多核苷酸[聚（A）、聚（C）和聚（U）]降解的影响。精胺和亚精胺刺激核糖核酸酶II对聚（C）的降解，而核糖核酸酶II对聚（A）的降解不受多胺影响。在我们的标准实验条件下，多胺对核糖核酸酶II降解聚（U）有轻微抑制作用。精胺和亚精胺对聚（C）降解的刺激作用在无单价阳离子存在时出现，但在无二价阳离子存在时不出现。当多胺用作核糖核酸酶II的刺激剂时，在存在聚（G）等抑制剂的情况下，聚（C）降解与聚（U）降解的比率比不存在抑制剂时更高。虽然核糖核酸酶I对所有合成多核苷酸的降解都受到多胺的刺激，但多胺的刺激程度顺序为聚（C）＞聚（A）（见正文）＞聚（U）。然而，随着单价阳离子浓度的增加，多核苷酸之间刺激程度的差异减小。
