Relationship between Molecular Weight of T4 Phage-induced Deoxynucleotide Kinase and the Size of Its Messenger Ribonucleic Acid

Abstract

Abstract T4 phage-induced deoxynucleotide kinase was purified to homogeneity as revealed by polyacrylamide gel electrophoresis. The molecular weight of this enzyme was estimated to be about 52,000 by the technique of Sephadex G-200 column chromatography. Enzyme denatured with 2-mercaptoethanol and sodium dodecyl sulfate also showed a single band after electrophoresis in an acrylamide gel containing sodium dodecyl sulfate. In the latter case, the molecular weight was calculated to be approximately 23,000, suggesting that the native enzyme is composed of two identical subunits. The messenger RNA for deoxynucleotide kinase produced in vivo has been found to be present in two relatively sharp bands that sediment in sucrose density gradients with a coefficient of 15 S and 12 S. This RNA, as well as unfractionated RNA, could direct in vitro the synthesis of deoxynucleotide kinase. The molecular weight of the enzyme synthesized in vitro was determined by gel filtration chromatography and found to be 48,000, approximately the same value as that found for the in vivo enzyme. The kinase messenger in 12 S RNA is believed to be transcribed from T4 DNA as a monocistronic unit. However, kinase messenger also appears in di- or polycistronic form since 15 S RNA is large enough to code for the synthesis of the kinase and at least one other protein.