Gates F T, Linn S
J Biol Chem. 1977 May 10;252(9):2802-7.
An endonuclease which is active upon DNA exposed to ultraviolet light at a photoproduct other than thymine dimers has been extensively purified from Escherichia coli. The small (2.7 S) enzyme is active in the presence of EDTA, has a neutral pH optimum, and is inhibited by tRNA and 1 M NaCl. It has no detectable exonuclease, DNA-N-glycosidase, or ribonuclease activities. The enzyme also nicks duplex DNA exposed to OsO4, x-rays, or acid, but it does not act upon undamaged DNA or irradiated single-stranded DNA. The majority of sites of action in DNA exposed to ultraviolet light or OsO4 appear to be alkali-stable, but those in DNA exposed to x-rays or acid are not. The incisions created by the endonuclease contain 5'-phosphate termini. The enzyme is possibly the same as E. coli endonuclease III described by Radman (Radman, M. (1976) J. Biol. Chem. 251, 1438-1445), but it is distinguishable from the other endodeoxyribonucleases described from that organism.
一种对暴露于紫外线的DNA在除胸腺嘧啶二聚体以外的光产物处具有活性的内切核酸酶已从大肠杆菌中得到广泛纯化。这种小（2.7 S）的酶在EDTA存在下具有活性，最适pH为中性，并且受到tRNA和1 M NaCl的抑制。它没有可检测到的外切核酸酶、DNA-N-糖苷酶或核糖核酸酶活性。该酶也能切割暴露于四氧化锇、X射线或酸的双链DNA，但对未受损的DNA或经辐射的单链DNA不起作用。暴露于紫外线或四氧化锇的DNA中的大多数作用位点似乎对碱稳定，但暴露于X射线或酸的DNA中的作用位点则不然。内切核酸酶产生的切口含有5'-磷酸末端。该酶可能与拉德曼描述的大肠杆菌内切核酸酶III相同（拉德曼，M.（1976年）《生物化学杂志》251，1438 - 1445），但它与从该生物体中描述的其他脱氧核糖核酸内切酶不同。
