Exonuclease I acts specifically on single-stranded DNA degrading it processively in the 3'- to 5'-direction, producing 5'-mononucleotides. Applications include eliminating residual single-stranded DNA containing a 3'-terminus, measuring endonucleolytic cleavage of covalently closed circular (ccc) ssDNA, measuring DNA helicase activity.

• 3'→5' single-stranded exonuclease
• Inactivated by heating at 80°C for 15 minutes
• Active in PCR buffers
• Easily soluble in cold water and hot water

Digestion of single-stranded DNA by Exonuclease I releases deoxyribonucleoside 5'-mono-phosphates leaving 5'-terminal dinucleotides intact. DNA strands with terminal 3'-OH groups blocked by phosphoryl or acetyl groups are not removed. Monomeric 54.5 kDa bacterial exonuclease I recombinantly expressed in E. coli. One unit of the enzyme catalyzes the release of 10 nmol of acid soluble nucleotides in 30 minutes at 37°C.

Free of contaminating endonucleases, double-stranded exonucleases and ribonucleases. Greater than 95% pure as determined by SDS-PAGE.

illustra Exonuclease I, used together with illustra Alkaline Phosphatase for inactivation of dNTPs, provides effective cleanup of PCR reactions for subsequent use in DNA sequencing.