A spectroscopic and electron microscopic examination of the highly condensed DNA structures formed by denaturation in Mg(ClO4)2
| Autor: | Gary S. Ott, Deepak Bastia, William R. Bauer |
|---|---|
| Rok vydání: | 1978 |
| Předmět: |
Electron density
Perchlorates Magnesium Temperature Formaldehyde DNA Single-Stranded chemistry.chemical_element Nucleic Acid Denaturation Coliphages Biochemistry Genetics and Molecular Biology (miscellaneous) Absorbance Microscopy Electron chemistry.chemical_compound Crystallography chemistry Spectrophotometry Duplex (building) Intramolecular force DNA Viral Mutation Molecule DNA |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Nucleic Acids and Protein Synthesis. 518:216-232 |
| ISSN: | 0005-2787 |
| Popis: | 1. 1. Thermal denaturation in 1.5 M Mg(ClO4)2 of the DNA from bacteriophage λ results in four well-separated subtransitions, as monitored by the accompanying increase in absorbance. The midpoint of the hyperchromic spectrum is significantly lowered compared to either 1.5 M MgCl2 or 3.0 M NaClO4. 2. 2. The first two subtransitions are associated with the melting of the A · T-richest regions of the λ DNA, as revealed by electron micrographs following fixation with formaldehyde. 3. 3. Commencing with the third subtransition, an unusual DNA structure is observed in electron micrographs. In this structure the A · T-rich half of the molecule appears completely condensed, whereas the G · C-rich half remains native. 4. 4. During the fourth subtransition DNA molecules condense completely and eventually aggregate to form extremely high molecular weight particles containing centers of electron density. Tendrils of DNA, primarily duplex, radiate outward from these centers. 5. 5. The aggregation may be reversed by the removal of magnesium. The intramolecular condensation may be at least partly reversed by increasing the Mg(ClO4)2 concentrations to saturating levels. |
| Databáze: | OpenAIRE |
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