title: Stereochemical course of hydrolysis of DNA by exonuclease I from Escherichia coli.
abstract: Exonuclease I has been purified from an overproducing strain of Escherichia coli K12 [Prasher, D. C., Conarro, L., & Kushner, S. R. (1983) J. Biol. Chem. 258, 6340-6343]. The enzyme hydrolyzes deoxyribonucleic acids that contain chiral phosphorothioate diester linkages, and the stereochemical course of the reaction is inversion of configuration at phosphorus. This result is most consistent with hydrolysis occurring via the direct attack of water on a phosphorothioate diester rather than through the intermediacy of a covalent nucleotidyl-enzyme intermediate. This finding represents the first example of a processive exonuclease whose stereochemical pathway has been determined.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D004247:DNA; D004926:Escherichia coli / Q000201:enzymology*; D005090:Exodeoxyribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D007202:Indicators and Reagents; D007700:Kinetics; D009838:Oligodeoxyribonucleotides; D011089:Polydeoxyribonucleotides; D013379:Substrate Specificity
chemical_list: D007202:Indicators and Reagents; D009838:Oligodeoxyribonucleotides; D011089:Polydeoxyribonucleotides; D004247:DNA; D005090:Exodeoxyribonucleases; C028450:exodeoxyribonuclease I