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Nanotribology Results Show that DNA Forms a Mechanically Resistant 2D Network in Metaphase Chromatin Plates
- Source :
- Biophysical Journal. 99(12):3951-3958
- Publication Year :
- 2010
- Publisher :
- Elsevier BV, 2010.
-
Abstract
- In a previous study, we found that metaphase chromosomes are formed by thin plates, and here we have applied atomic force microscopy (AFM) and friction force measurements at the nanoscale (nanotribology) to analyze the properties of these planar structures in aqueous media at room temperature. Our results show that high concentrations of NaCl and EDTA and extensive digestion with protease and nuclease enzymes cause plate denaturation. Nanotribology studies show that native plates under structuring conditions (5 mM Mg2+) have a relatively high friction coefficient (μ ≈ 0.3), which is markedly reduced when high concentrations of NaCl or EDTA are added (μ ≈ 0.1). This lubricant effect can be interpreted considering the electrostatic repulsion between DNA phosphate groups and the AFM tip. Protease digestion increases the friction coefficient (μ ≈ 0.5), but the highest friction is observed when DNA is cleaved by micrococcal nuclease (μ ≈ 0.9), indicating that DNA is the main structural element of plates. Whereas nuclease-digested plates are irreversibly damaged after the friction measurement, native plates can absorb kinetic energy from the AFM tip without suffering any damage. These results suggest that plates are formed by a flexible and mechanically resistant two-dimensional network which allows the safe storage of DNA during mitosis.
- Subjects :
- Friction
Analytical chemistry
Biophysics
Sodium Chloride
Microscopy, Atomic Force
Nucleic Acid Denaturation
chemistry.chemical_compound
Chromosomes, Human
Humans
Nanotechnology
Denaturation (biochemistry)
Lubricant
Metaphase
Edetic Acid
Ions
Nuclease
Deoxyribonucleases
Nucleic Acid
biology
DNA
Electrostatics
Chromatin
chemistry
biology.protein
Nanotribology
HeLa Cells
Peptide Hydrolases
Micrococcal nuclease
Subjects
Details
- ISSN :
- 00063495
- Volume :
- 99
- Issue :
- 12
- Database :
- OpenAIRE
- Journal :
- Biophysical Journal
- Accession number :
- edsair.doi.dedup.....f1e96a93e9284f48391fca0b5047d936
- Full Text :
- https://doi.org/10.1016/j.bpj.2010.11.015