STUDIES ON ESCHERICHIA-COLI X-RAY ENDONUCLEASE SPECIFICITY - ROLES OF HYDROXYL AND REDUCING RADICALS IN PRODUCTION OF DNA LESIONS
STUDIES ON ESCHERICHIA-COLI X-RAY ENDONUCLEASE SPECIFICITY - ROLES OF HYDROXYL AND REDUCING RADICALS IN PRODUCTION OF DNA LESIONS
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DOI：
10.2307/3574440
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发表时间：
1977-01-01
影响因子：
3.4
通讯作者：
WALLACE, SS
中科院分区：
文献类型：
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作者：
ARMEL, PR;STRNISTE, GF;WALLACE, SS
通过PM2I型DNA向II型DNA的转化，比较了X射线照射、X射线照射加碱处理或X射线照射后与大肠杆菌X-射线内切酶孵育引起的DNA链断裂。羟基自由基参与了碱不稳定损伤的形成，并在较小程度上引起了单链断裂。所有碱不稳定的病变也是酶敏感部位。当通过清除自由基降低羟基自由基的有效浓度时，还原物种似乎产生了不耐碱的酶敏感部位。胰蛋白内酯-葡萄糖-酵母提取液，用于尝试模拟细胞条件，防止链断裂、碱不稳定损伤和非碱不稳定酶敏感损伤。E.ColiX-射线内切酶识别OsO4诱导的DNA损伤，这些损伤与电离辐射产生的胸腺嘧啶的辐射分解产物相同。
DNA strand breakage induced by X irradiation, by X irradiation and alkali treatment, or by X irradiation and subsequent incubation with E. coli X-ray endonuclease was measured by the conversion of PM2 Type I DNA to Type II. The hydroxyl radical mediated the formation of alkali-labile lesions and to a lesser extent simple strand breaks. All alkali-labile lesions were also enzyme-sensitive sites. When the effective concentration of hydroxyl radicals was reduced by radical scavenging, reducing species appeared to produce enzyme sensitive sites which were not alkali labile. Tryptone-glucose-yeast extract medium, which was used in an attempt to simulate cellular conditions, protected against strand breakage, alkali-labile lesions and non-alkali-labile enzyme-sensitive damages. The E. coli X-ray endonuclease recognized OsO4 induced DNA damages which are identical to the radiolysis products of thymine produced by ionizing radiation.