||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. Kindly note that, as of October 4th 2021, the link to the pdf version of the reference article (Ruet et al., 1970) from PUBMED is broken. Through Google Scholar, however, the pdf of the article can be accessed.