Stereochemical studies of the .beta.-elimination reactions at aldehydic abasic sites in DNA: endonuclease III from Escherichia coli, sodium hydroxide, and Lys-Trp-Lys

Abhijit Mazumder, John A. Gerlt, Michael J. Absalon, JoAnne Stubbe, Richard P. Cunningham, Jane Withka, Philip H. Bolton
1991 Biochemistry  
The D N A strand cleavage reaction catalyzed by endonuclease I11 from Escherichia coli (endo 111) on the 3'-side of aldehyde abasic sites proceeds by a syn P-elimination involving abstraction of the 2'-pro-S proton and formation of a trans a,@-unsaturated aldose product; we previously reported the same stereochemical 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)
more » ... lton, P. H. (1989) J. Am. Chem. SOC. 11 1, 8029-80301. Since the UV endo V does not contain an 4Fe-4S center, the 4Fe-4S center present in endo 111 need not be assigned a unique role in the @-elimination reaction. The P-elimination reactions that occur under alkaline conditions (0.1 N NaOH) and in the presence of the tripeptide Lys-Trp-Lys proceed by anti @-elimination mechanisms involving abstraction of the 2'-pro-R proton and formation of a trans a,P-unsaturated aldose product. The different stereochemical outcomes of the enzymatic and nonenzymatic P-elimination reactions support the hypothesis that the enzyme-catalyzed reactions may involve generalbase-catalyzed abstraction of the 2'-pro-S proton by the internucleotidic phosphodiester leaving group.
doi:10.1021/bi00218a033 pmid:1846560 fatcat:vjmpwzhjnjdthie4ersfuduzpe