STEREOCHEMICAL STUDIES OF THE BETA-ELIMINATION REACTIONS AT ALDEHYDIC ABASIC SITES IN DNA - ENDONUCLEASE III FROM ESCHERICHIA-COLI, SODIUM-HYDROXIDE, AND LYS-TRP-LYS
STEREOCHEMICAL STUDIES OF THE BETA-ELIMINATION REACTIONS AT ALDEHYDIC ABASIC SITES IN DNA - ENDONUCLEASE III FROM ESCHERICHIA-COLI, SODIUM-HYDROXIDE, AND LYS-TRP-LYS
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DOI：
10.1021/bi00218a033
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发表时间：
1991-01-29
期刊：
影响因子：
2.9
通讯作者：
BOLTON, PH
中科院分区：
文献类型：
--
作者：
MAZUMDER, A;GERLT, JA;BOLTON, PH
由来自大肠杆菌的核酸内切酶 III (endo III) 在醛脱碱基位点 3' 侧催化的 DNA 链裂解反应通过顺式 β-消除进行，涉及提取 2'-pro-S 质子并形成反式 α-β-不饱和醛糖产物；我们之前报道了噬菌体 T4 的 UV 核酸内切酶 V (UV endo V) 催化反应的相同立体化学过程 [Mazumder, A., Gerlt, J.A., Rabow, L., Absalon, M.J., Stubbe, J., & Bolton, P.H.(1989)J.是。化学。 苏克。 111、8029-8030]。 由于UV endo V不包含4Fe-4S中心，因此endo III中的存在不需要在β-消除反应中发挥独特的作用。 在碱性条件 (0.1 N NaOH) 和三肽 Lys-Trp-Lys 存在下发生的 β-消除反应通过抗 β-消除机制进行，涉及 2'-pro-R 质子的提取和反式 α-β-不饱和醛糖产物的形成。 酶促和非酶促β-消除反应的不同立体化学结果支持这样的假设：酶催化反应可能涉及核苷酸间磷酸二酯离去基团对2'-pro-S质子的一般碱催化抽象。
The DNA strand cleavage reaction catalyzed by endonuclease III from Escherichia coli (endo III) on the 3'-side of aldehyde abasic sites proceeds by a syn beta-elimination involving abstraction of the 2'-pro-S proton and formation of a trans alpha-beta-unsaturated aldose product; we previously reported the same stereo-chemical course for the reaction catalyzed by UV endonuclease V from bacteriophage T4 (UV endo V) [Mazumder, A., Gerlt, J.A., Rabow, L., Absalon, M.J., Stubbe, J., & Bolton, P.H.(1989)J. Am. Chem. Soc. 111, 8029-8030]. Since the UV endo V does not contain an 4Fe-4S center, present in endo III need not be assigned a unique role in the beta-elimination reaction. The beta-elimination reactions that occur under alkaline conditions (0.1 N NaOH) and in the presence of the tripeptide Lys-Trp-Lys proceed by anti beta-elimination mechanism involving abstraction of the 2'-pro-R proton and formation of a trans alpha-beta-unsaturated aldose product. The different stereochemical outcomes of the enzymatic and nonenzymatic beta-elimination reactions support the hypothesis that the enzyme-catalyzed reactions may involve general-base-catalyzed abstraction of the 2'-pro-S proton by the internucleotidic phosphodiester leaving group.