Thymine dimer(胸腺嘧啶二聚体).uy induces a cyclobutane(环丁烷)ring between adjacent T. 3 P 5 cyclobutane ring CH3 CH3 CH3 Radiation damage 1 thymine dimer 2024
2025/5/15 17 Thymine dimer (胸腺嘧啶二聚体）. UV induces a cyclobutane (环丁烷) ring between adjacent T. Radiation damage 1
Gamma radiation and X-rays (ionizing radiation,电离辐射)cause double-strand breaks(DSB)and are particularly hazardous (hard to be repaired). Radiation damage 2 2025/5/15 18
2025/5/15 18 Gamma radiation and X-rays (ionizing radiation，电离辐射) cause double-strand breaks (DSB) and are particularly hazardous (hard to be repaired). Radiation damage 2
1.3 Mutations are also caused by base analogs(碱基类似物)and intercalating agents(嵌入剂) >Base analogs:similar enough to the normal bases to be processed by cells and incorporated into DNA during replication. >But they form base pair differently, leading to mispairing during replication. >The most mutagenic base analog is 5-bromoUracil(5-BrU)(5-溴尿嘧啶). 2025/5/15 19
2025/5/15 19 1.3 Mutations are also caused by base analogs (碱基类似物) and intercalating agents(嵌入剂) ➢Base analogs: similar enough to the normal bases to be processed by cells and incorporated into DNA during replication. ➢But they form base pair differently, leading to mispairing during replication. ➢The most mutagenic base analog is 5-bromoUracil (5-BrU) (5-溴尿嘧啶)
a Br Br H○ N nnH -N G H 酮异构体 烯醇异构体 H 5-bromouracil 5-bromouracil guanine (keto tautomer) (enol tautomer) Base analogues Copyright 2004 Pearson Education,Inc.,publishing as Benjamin Cummings 2025/5/15 20
2025/5/15 20 Base analogues 酮异构体 烯醇异构体
>Intercalating agents are flat molecules containing several polycyclic rings that interact with the normal bases in DNA through hydrogen bonds and base stacking. 2025/5/15 21
2025/5/15 21 ➢Intercalating agents are flat molecules containing several polycyclic rings that interact with the normal bases in DNA through hydrogen bonds and base stacking