Purification of calf thymus RNA polymerase II for in vitro transcription studies.

A procedure for the purification of a large amount of RNA polymerase II (RNAP II) from calf thymus is described. This procedure results in an approximately 1400-fold purification with 40% yield of enzyme in 60 h. The partially purified enzyme is highly suitable for in vitro transcription studies in a cell-free system utilizing HeLa S-100. This method for RNAP II purification would find significant applications in in vitro studies for the analysis of factors modulating eukaryotic transcription.