Exonuclease III is an exonuclease that acts on double-stranded DNA, progressively removing mononucleotides from the 3′-OH terminus. The preferred substrates are blunt-ended or 5′-overhanging DNAs, but the enzyme can also act at nicks in double-stranded DNA to generate single-strand gaps. Because it has no activity on single-stranded DNA, it is difficult to cleave 3′ overhangs. The extent of 3′-to-5′ exonuclease digestion varies with the length of the 3′ overhang; overhangs of four bases or longer are difficult to cleave. This property can be used to produce single-stranded DNA in a defined direction by designing linearized DNA with one non-cleavable end (3′ overhang) and one cleavable end (blunt or 5′ overhang); under these conditions, Exonuclease III will digest only one strand. The activity of Exonuclease III depends partly on DNA double-helix structure and varies with sequence (C > A=T > G). In addition, this enzyme also exhibits RNase H, 3′-phosphatase, and apurinic/apyrimidinic (AP) site-specific endonuclease activities. Product Information Catalog No. Size 14525ES90 / 14525ES96 5,000 U / 25,000 U Component Information Component No. Component Name 14525ES90 14525ES96 14525-A Exonuclease III (100 U/μL) 50 μL 5 × 50 μL 14525-B 10× Exo III Buffer 500 μL 5 × 500 μL Feature The preferred substrates are blunt-ended or 5′-overhanging DNAs, but the enzyme can also act at nicks in double-stranded DNA to generate single-strand gaps. Because it has no activity on single-stranded DNA, it is difficult to cleave 3′ overhangs. The extent of 3′-to-5′ exonuclease digestion varies with the length of the 3′ overhang; overhangs of four bases or longer are difficult to cleave. Figure Case Study 1: Performance Verification Performance verification: The digestion efficiency of double-stranded substrate is superior to that of an imported brand, and complete degradation can be achieved with a low enzyme amount. Figure 1: Comparison of double-stranded DNA digestion capacity between Yeasen and imported brand A* Exonuclease III. [Note]: 1 μg of λDNA was added to a 50 μL reaction system. Different amounts (0.06, 0.31, 0.63, 1.25, 2.5, 5, 10, 20 U) of Yeasen and imported brand A* Exonuclease III were used and incubated at 37°C for 30 min. The enzyme was inactivated by adding EDTA to a final concentration of 5.5 mM. Single-stranded DNA degradation was detected by agarose gel electrophoresis. The results show that the single-stranded DNA digestion capacity of Yeasen Exonuclease III is superior to that of imported brand A*.