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The inhibitory effect of Zn2+ on poly(ADP-ribose) polymerase activity and its reversal
Abstract:
Zn2+ inhibits purified poly(ADP-ribose) polymerase (50% inhibition at 10 microM). Furthermore poly (ADP-ribose) polymerase present in nuclei and metaphase chromosome clusters is also inhibited by Zn2+. The inactivated enzyme could be re-activated by dithiothreitol. The concentration of Zn2+ needed to affect the enzyme activity in the organelles is sufficiently low for it to have a possible role in controlling the activity of this chromatin-bound enzyme.
Insights
Zinc ions (Zn2+) inhibit poly(ADP-ribose) polymerase, an enzyme crucial for DNA repair. This inhibition occurs in purified enzymes and within cell nuclei, suggesting a role for zinc in regulating this key enzyme.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Poly(ADP-ribose) polymerase (PARP) is a critical enzyme involved in DNA repair and genomic stability.
- Chromatin-bound enzymes play vital roles in regulating gene expression and DNA metabolism.
Purpose of the Study:
- To investigate the effect of zinc ions (Zn2+) on the activity of poly(ADP-ribose) polymerase.
- To determine if Zn2+ can modulate PARP activity in both purified and cellular contexts.
Main Methods:
- Enzyme inhibition assays using purified poly(ADP-ribose) polymerase.
- Analysis of PARP activity within isolated nuclei and metaphase chromosome clusters.
- Enzyme re-activation studies using dithiothreitol.
Main Results:
- Zn2+ demonstrated significant inhibition of purified poly(ADP-ribose) polymerase, with 50% inhibition observed at 10 microM.
- Poly(ADP-ribose) polymerase activity within cell nuclei and chromosome clusters was also inhibited by Zn2+.
- The Zn2+-induced inactivation of the enzyme was reversible by treatment with dithiothreitol.
Conclusions:
- Zinc ions can directly inhibit poly(ADP-ribose) polymerase activity.
- The observed inhibition of nuclear and chromosomal PARP by Zn2+ suggests a potential physiological role for zinc in regulating this enzyme.
- The low concentration of Zn2+ required for inhibition indicates its possible function in controlling chromatin-bound enzyme activity.