1) Incubate the PUREfrex^® reaction mixture by directly heating the reaction tube with heat block or water bath. Gas-phase chamber (e.g., incubator) takes time to warm the reaction mixture and the yield may be reduced.

2) Some of the components of the kit may lose their activity. Store the kit at a proper temperature to prevent loss of activity. Divide the reagents into aliquots to avoid the repeated freeze-thaw cycles as much as possible.

3) Cysteine may not have been added. In PUREfrex^® 2.1, you can freely adjust the amount of reducing agents (Cysteine, DTT and GSH, etc.), but be sure to add Cysteine, which is a material of protein.