Phi29 is a polymerase used for multiple displacement amplification (MDA) procedures in molecular biology.
Phi29 works by using random hexamers which under the right buffer conditions will hybridize with the DNA template. The Phi29 polymerase is then able to begin elongation from multiple sites producing DNA concatamers. Due to its "cow-catch" capabilities, Phi29 is also able to displace double strands as it moves along the template.
Rolling circle amplification is an isothermal process using short DNA and RNA primers to amplify a circular template, forming concatemers containing repeats that are complementary to the circular template. The reaction is powered by a Phi29 polymerase.