Waldeck W, Chowdhury K, Gruss P, Sauer G
Biochim Biophys Acta. 1976 Mar 4;425(2):157-67. doi: 10.1016/0005-2787(76)90021-6.
SV40 DNA FO I is randomly cleaved by S1 nuclease both at moderate (50 mM) and higher salt concentrations (250 mM NaC1). Full length linear S1 cleavage products of SV40 DNA when digested with various restriction endonucleases revealed fragments that were electrophoretically indistinguishable from the products found after digestion of superhelical SV40 DNA FO I with the corresponding enzyme. Concordingly, when the linear S1 generated duplexes were melted and renatured, circular duplexes were formed in addition to complex larger structures. This indicated that cleavage must have occurred at different sites. The double-strand-cleaving activity present in S1 nuclease preparations requires circular DNA as a substrate, as linear SV40 DNA is not cleaved. With regard to these properties S1 nuclease resembles some of the complex type I restriction nucleases from Escherichia coli which also cleave SV40 DNA only once, and, completely at random.
SV40 DNA F0I在中等盐浓度（50 mM）和较高盐浓度（250 mM NaCl）下均会被S1核酸酶随机切割。用各种限制性内切酶消化时，SV40 DNA的全长线性S1切割产物显示出的片段，在电泳上与用相应酶消化超螺旋SV40 DNA F0I后得到的产物无法区分。相应地，当线性S1产生的双链体解链并复性时，除了形成复杂的更大结构外，还形成了环状双链体。这表明切割一定发生在不同的位点。S1核酸酶制剂中存在的双链切割活性需要环状DNA作为底物，因为线性SV40 DNA不会被切割。就这些特性而言，S1核酸酶类似于大肠杆菌中的一些复杂的I型限制性核酸酶，后者也仅对SV40 DNA切割一次，并且完全是随机切割。
