Sedimentation analysis of ribonucleotide reductase activity in extracts of Pseudomonas stutzeri

Analysis of ribonucleotide reductase and DNA polymerase activities in extracts of Pseudomonas stutzeri by centrifugation in discontinuous sucrose gradients indicated that these two enzymes are associated with two different high molecular weight cellular components. In addition, 95% of the ribonucleotide reductase activity was pelleted by centrifugation of extracts for 4 hr at 200,000 X G. The reductase activity remained particulate (sedimentable) following sonication whereas some 90% of the DNA polymerase activity was rendered soluble (non-sedimentable) by this technique. This data indicate that the P. stutzeri ribonucleotide reductase is not a cytosolic enzyme, but is associated with a macromolecular component in the cell.