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dna的復(fù)制ppt課件-展示頁

2025-05-10 18:05本頁面
  

【正文】 mas. ?DNA聚合酶 II:沒有 5′ 3 ′ 外切核酸酶活性, 次要的 DNA修復(fù)酶 ?DNA聚合酶 III: 是真正的 DNA復(fù)制酶 ?多亞基 ?多層次組裝 ?DNA聚合酶 IV和 V:參與 SOS修復(fù) 2. DNA聚合酶 III的結(jié)構(gòu): α DNA聚合酶 ε 3’5’核酸外切酶 θ 激活 ε外切酶活性 τ 使核心酶結(jié)合為二聚體;結(jié)合 γ復(fù)合物 γ 結(jié)合 ATP δ 與 β亞基結(jié)合 δ ’ 與 γ和 δ亞基結(jié)合 χ 與 SSB 蛋白結(jié)合 ψ 與 χ和 γ亞基結(jié)合 β sliding clamp(滑動(dòng)夾環(huán)) 核心酶 Pol III Pol III’ Pol III* γ 復(fù) 合 體 β sliding clamp 二、解螺旋酶 (helicase): A helicase is an enzyme that uses energy provided by NTP hydrolysis to separate the strands of a nucleic acid duplex 三、 SSB蛋白(單鏈結(jié)合蛋白) The singlestrand binding protein (SSB) attaches to singlestranded DNA, thereby preventing the DNA from forming a duplex ?防止單鏈復(fù)性 ?維持單鏈剛性狀態(tài) ?避免單鏈降解 ?The SSB binds as a monomer, but typically in a cooperative manner in which the binding of one protein molecule makes it much easier for another to bind 四、引發(fā)酶 (primase): The primase is a type of RNA polymerase that synthesizes short segments of RNA that will be used as primers for DNA replication. 為什么 DNA的合成需要 RNA引物? 五、旋轉(zhuǎn)酶 (gyrase ): a Type II topoisomerase, acts to overe the torsional stress imposed upon unwinding by introducing negative supercoils at the expense of ATP hydrolysis. ?復(fù)制叉前進(jìn)帶來扭曲張力 ?拓?fù)洚悩?gòu)酶 II: 引入負(fù)超螺旋 六、 DNA連接酶 ( DNA ligases ) DNA ligase makes a bond between an adjacent 3’OH and 5’ phosphate end where there is a nick in one strand of duplex DNA . 酶活化 AMP轉(zhuǎn)移 3′ OH親核攻擊 第三節(jié) DNA的復(fù)制過程 一、原核生物的復(fù)制( ) (一)復(fù)制的起始: 1. 復(fù)制原點(diǎn): Ori C
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