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Ribonucleotide reduction in intact human diploid fibroblasts
Journal of Cellular Physiology
|October 1, 1980
Summary
Researchers developed a new method to measure ribonucleotide reductase activity in human cells. This technique helps understand how hydroxyurea affects cell growth and could aid genetic studies.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Ribonucleotide reductase activity is crucial for DNA synthesis.
- Limited studies exist on this enzyme's activity in human tissues.
- Understanding its function in normal human cells is vital.
Purpose of the Study:
- To establish a method for measuring ribonucleotide reductase activity in human diploid fibroblasts.
- To characterize the enzyme's properties and its response to effectors.
- To investigate the impact of hydroxyurea on enzyme activity and cell viability.
Main Methods:
- Developed a rapid assay for purine and pyrimidine ribonucleotide reduction.
- Characterized enzyme kinetics using various effectors (ATP, dGTP, dATP, dithiothreitol).
- Determined apparent Km values for ADP and CDP, and Ki values for hydroxyurea.
Main Results:
- Established a reliable method for ribonucleotide reductase assay in human fibroblasts.
- Determined kinetic parameters (Km) for ADP (0.1 mM) and CDP (0.04 mM).
- Hydroxyurea inhibited the enzyme noncompetitively (Ki: 0.40-0.41 mM) and showed cytotoxic effects correlated with enzyme inhibition.
Conclusions:
- The new method enables ribonucleotide reductase studies in low numbers of human diploid cells.
- Hydroxyurea's inhibitory effect and cytotoxicity in normal cells were quantified.
- Findings support the utility of this method for genetic and biochemical research.