Gateway BP Clonase® enzyme contains both Int (Integrase) and IHF (Integration Host Factor) proteins that catalyze the in vitro recombination of PCR products or DNA segments from clones (containing attB sites) and a Donor vector (containing attP sites) to generate Entry clones. BP Clonase® II enzyme format is a single mix of both enzyme and buffer to ensure enzyme stability and enable convenient 10μl reaction set up with fewer pipetting steps, which both maximize recombination efficiency and minimize pippetting. The original format of BP Clonase enzyme is the stand alone enzyme blend and reaction buffer provided in separate tubes.