Using proteases to control star activity of restriction enzymes

A process of inhibiting or preventing star activity by a restriction endonuclease comprising:

• digesting an oligomer using a reaction mixture comprising a restriction endonuclease, buffer and oligomer;
• including in the reaction mixture proteinase K, endoproteinase LysC and/or trypsin buffer and oligomer, in order to inhibit or prevent star activity by the restriction endonuclease;
• and
• terminating the digestion by adding a stopping solution including a loading dye.