Restriction endonucleases digesting DNA in PCR buffer

Six commonly used restriction endonucleases (REs) (Acc Ⅰ, Ban Ⅱ, EcoR Ⅰ, Hind Ⅲ, Sac Ⅰ, Sca Ⅰ) were tested for their ability to directly digest DNA completely in the Polymerase Chain Reaction (PCR) buffers. The results showed that: with the requirement for additional magnesium supplemented as activator, REs, except EcoR I appeared star activity, completely digested unmethylated lambda DNA after overnight incubation in PCR buffer and functioned as equally well as in recommended Restriction Enzyme Buffer provided with each enzyme; all REs tested completely digested PCR products in PCR buffer, it implied digestion of PCR products may often be performed directly in the PCR tube without the requirement for any precipitation or purification steps; and the concentration of MgCl2 from 2.5 mmol·L^-1 to 10 mmol·L^-1 did not significantly affect activity of REs in PCR buffer. This simplified method for RE digestion of PCR products could have applications in restriction fragment length polymorphism (RFLP) analysis and single-stranded conformational polymorphism (SSCP) analysis of large PCR products. However, usage of this procedure for cloning applications needs further data.