||P.170 left column bottom paragraph: "From the calibration curve given in fig.2, the molecular weight of RNA polymerase is estimated as 480,000±30,000 daltons, whereas the core enzyme is oligomeric and runs as a protein heavier than 800,000 daltons. The excised binary complex is estimated as 420,000±30,000 daltons and the σ subunit 80,000±5,000 daltons. The DNase excited initiation complex corresponding to RNA polymerase incubated with T4 DNA and ATP, UTP, CTP, behaves also as a material of 420,000 daltons, interestingly enough just as the DNase treated complex between core enzyme and T4 DNA." Enzymes that require a cofactor to show full activity are named apoenzymes (or apoproteins). An apoenzyme with its cofactor is named holoenzyme. The cofactor of RNA Polymerase is sigma factor.