Pool sizes of deoxyribonucleoside triphosphates (dNTPs) in cultured cells are tightly regulated by i.al., the allosteric control of ribonucleotide reductase. We now determine the in situ activity of this enzyme from the turnover of the deoxycytidine triphosphate (dCTP) pool in rapidly growing 3T6 mouse fibroblasts, as well as in cells whose DNA replication was inhibited by aphidicolin or ametho...

The relationship between ribonucleotide reductase and tumor growth rate was measured in a series of rat hepatomas of different growth rates. An excellent correlation was found between tumor growth rate and the specific activity of ribonucleotide reductase. Differences of ZOO-fold in enzyme specific activities exist between the very fast and the slow growing hepatomas. This represents the larges...

A somatic mutant cell line of murine T-lymphoma cells (S49), dGuo-200-1, has been isolated and contains a ribonucleotide reductase (Ullman, B., Clift, S. M., Gudas, L. J., Levinson, B. B., Wormsted, M. A., and Martin, D. W., Jr. (1980) J. Biol. Chem 255,8308-8314) with altered allosteric properties. The enzyme in dGuo200-1 extracts was inhibited only 50% by the allosteric inhibitor, dATP. Thus,...

The levels of ribonucleotide reductase activity (measured as the conversion of 3H-cytosine monophosphate to 3HdCMP) in cell-free extracts of partially synchronized cultures of L cells were measured as the cells moved through the division cycle. A strict parallelism was found between the measured enzyme levels and the fractions of the population that were forming DNA. This relationship between e...

The ribonucleotide reductase system of Escherichia coli B participates in the biosynthesis of DNA by reducing ribonucleoside diphosphates to the corresponding deoxyribonucleotides. The enzyme is regulated in a complicated way by allosteric modifiers. We now find that infection of E. coli with the bacteriophage T4 results in the appearance of a new ribonucleotide reductase system which shows a s...

Ribonucleotide reductases (RRs or RNRs) catalyze the reduction of OH group on 2nd carbon ribose, reducing four ribonucleotides (NTPs) to corresponding deoxyribonucleotides (dNTPs) promote DNA synthesis. Large viruses, such as herpesviruses and poxviruses, could benefit their replication through increasing dNTPs via expression viral RRs. Little is known regarding relationship between cellular RR...