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Glutaredoxin from calf thymus. Purification to homogeneity
The Journal of Biological Chemistry
|June 25, 1982
Summary
Researchers purified calf thymus glutaredoxin, essential for GSH-dependent ribonucleotide reduction. This purified protein showed high activity with calf thymus ribonucleotide reductase, demonstrating its biological role.
Area of Science:
- Biochemistry
- Molecular Biology
Background:
- Glutaredoxin is a key protein involved in cellular redox homeostasis.
- It plays a critical role in the GSH-dependent pathway for ribonucleotide reduction, essential for DNA synthesis.
Purpose of the Study:
- To purify calf thymus glutaredoxin to homogeneity.
- To characterize its biochemical properties and assess its activity with ribonucleotide reductase.
Main Methods:
- Purification involved ammonium sulfate precipitation and multiple chromatography steps (DEAE-cellulose, Sephadex G-50, CM-Sepharose).
- Homogeneity was confirmed by polyacrylamide gel electrophoresis and HPLC.
- Enzyme activity was assayed using GSH-disulfide transhydrogenase activity and kinetic analysis with ribonucleotide reductase.
Main Results:
- Calf thymus glutaredoxin was purified approximately 3000-fold to homogeneity.
- The purified protein has a molecular weight of approximately 11,000 Da and behaves as a neutral or slightly basic molecule.
- Glutaredoxin exhibited high affinity (Km = 6.0 x 10(-7) M) for calf thymus ribonucleotide reductase in the presence of GSH.
- Its activity with Escherichia coli ribonucleotide reductase was significantly lower (10% molecular activity).
Conclusions:
- Calf thymus glutaredoxin has been successfully purified and characterized.
- The enzyme demonstrates specific and efficient interaction with its homologous ribonucleotide reductase, highlighting species-specific enzyme-protein interactions.