Störl K, Störl H J
Akademie der Wissenschaften der DDR.
Biomed Biochim Acta. 1989;48(1):69-76.
A type I topoisomerase has been purified from Diplococcus pneumoniae using phosphocellulose and hydroxylapatite chromatography. The purified enzyme catalyses the relaxation of negatively supercoiled DNA. The relaxation requires Mg2+ and is favoured by 0.2 M monovalent cations. The enzyme does not exhibit catenating or supercoiling activities. Using circular pBR322 DNA from dam+- and dam- -hosts as substrates for the enzyme, the relaxation reaction proceeds with somewhat higher efficiency with plasmids containing methylated adenine in GATC sequences. Plasmids from dcm+- and dcm- -hosts show no difference in reactivity.
已使用磷酸纤维素和羟基磷灰石色谱法从肺炎双球菌中纯化出一种I型拓扑异构酶。纯化后的酶催化负超螺旋DNA的松弛。这种松弛需要Mg2+，并且在0.2 M单价阳离子存在时更有利。该酶不表现出连环或超螺旋活性。以来自dam+和dam-宿主的环状pBR322 DNA作为该酶的底物，对于在GATC序列中含有甲基化腺嘌呤的质粒，松弛反应的进行效率略高。来自dcm+和dcm-宿主的质粒在反应性上没有差异。
