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Analysis of DNA structure by hydroxyapatite columns and ethidium bromide fluorescence techniques. A comparative study
Arthritis and Rheumatism
|May 1, 1978
Summary
Most DNA preparations contain unwanted single-stranded regions, affecting radioimmunoassay results. Hydroxyapatite chromatography and ethidium bromide fluorescence revealed these structural impurities in duplex DNA samples.
Area of Science:
- Molecular Biology
- Biochemistry
- Analytical Chemistry
Background:
- Accurate structural characterization of DNA is crucial for molecular biology applications.
- Radioimmunoassays rely on specific DNA binding, which can be compromised by structural anomalies.
Purpose of the Study:
- To assess the structural integrity of duplex DNA preparations.
- To identify the presence of single-stranded DNA or regions within purported duplex DNA.
- To evaluate the impact of structural impurities on DNA binding assays.
Main Methods:
- Hydroxyapatite column chromatography for DNA separation.
- Ethidium bromide fluorescence assay for detecting single-stranded DNA.
- Analysis of synthetic poly dAT as a control duplex DNA.
Main Results:
- One DNA preparation showed significant single-stranded DNA contamination via hydroxyapatite chromatography.
- Five of six remaining preparations exhibited significant single-stranded regions using ethidium bromide fluorescence.
- Synthetic poly dAT confirmed to be structurally duplex.
- Single-stranded regions demonstrably influenced radioimmunoassay DNA binding outcomes.
Conclusions:
- Many duplex DNA preparations contain structural defects (single-stranded regions).
- These impurities can significantly interfere with sensitive molecular assays like radioimmunoassays.
- Rigorous structural validation of DNA is essential before use in binding studies.