Related Experiment Videos
Specific binding of calcium to soluble chromatin
Zeitschrift Fur Naturforschung. C, Journal of Biosciences
|September 1, 1986
Summary
Calcium ions (Ca2+) specifically bind to chromatin, neutralizing negative charges and influencing higher-order structures. This binding occurs even at high salt concentrations, impacting chromatin organization.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Chromatin structure is crucial for DNA regulation.
- The role of divalent cations, particularly calcium (Ca2+), in chromatin organization is not fully understood.
- Understanding cation binding is key to elucidating chromatin higher-order structure.
Purpose of the Study:
- To investigate the specific binding of calcium ions (Ca2+) to rat liver chromatin.
- To determine the influence of Ca2+ binding on chromatin structure and charge neutralization.
- To compare the effects of monovalent and divalent cations on chromatin.
Main Methods:
- Equilibrium dialysis studies using soluble rat liver chromatin.
- Sedimentation experiments.
- Radioactive 45Ca tracer to quantify calcium binding.
Main Results:
- Specific binding of Ca2+ to chromatin molecules was demonstrated.
- At low ionic strength, Ca2+ binding neutralizes over half of chromatin's negative charges (binding constant ~12 l/mM).
- Ca2+ specifically binds to chromatin even under high salt conditions (binding constant ~0.4 l/mM), while monovalent cations cause non-specific charge shielding.
Conclusions:
- Specific Ca2+ binding to chromatin plays a significant role in neutralizing negative charges.
- This neutralization mechanism likely explains how low concentrations of Ca2+ induce compact chromatin structures.
- Chromatin structure is modulated by both specific divalent cation binding and non-specific monovalent cation interactions.