Novel properties of Escherichia coli exonuclease III
- Resource Type
- Authors
- R Wu; R Roychoudhury
- Source
- Journal of Biological Chemistry. 252:4786-4789
- Subject
- chemistry.chemical_classification
Exonuclease III
biology
Oligonucleotide
Escherichia coli exonuclease III
Substrate (chemistry)
Cell Biology
Biochemistry
Hydrolysis
Enzyme
chemistry
Polynucleotide
Cleave
biology.protein
Molecular Biology
- Language
- ISSN
- 0021-9258
The specificity of hydrolysis of polynucleotide termini by Escherichia coli exonuclease III was studied with the use of oligothymidylate annealed to polydeoxyadenylate. The size of the products after 3' leads to 5'-hydrolysis of 5'-labeled substrate is temperature-dependent. At 25 degrees the enzyme can hydrolyze a polynucleotide chain up to the last 5'-terminal dinucleotide. A gradation of higher 5'-terminal oligonucleotides of defined chain lengths is produced after limit digestion by the enzyme when the temperature is raised between 25 degrees to 60 degrees. When the oligothymidylate was labeled at the 3'-ends with ribonucleotides, it was observed that exonuclease III can cleave a single or two consecutive ribonucleotides regardless of whether the ribonucleotides are base-paired or mismatched.