Helical repeat of DNA in solution. The V curve method.

Area of Science:

• Molecular Biology
• Biophysics
• Genetics

Background:

• The topological constraint of small DNA rings influences their electrophoretic mobility.
• Previous research documented a V-like dependence of mobility on topological constraint.
• This phenomenon offers a potential method for measuring DNA helical twist.

Purpose of the Study:

• To explore the V-like dependence of DNA ring electrophoretic mobility as a tool for measuring helical twist.
• To estimate the average helical periodicity of mixed-sequence DNA fragments.
• To compare DNA fragments and evaluate helical repeats of specific DNA inserts and methylation effects.

Main Methods:

• Electrophoretic mobility measurements of small DNA rings.
• Application of the V-like dependence to DNA fragments (350-1400 base pairs).
• Comparison of helical repeat estimates with previous techniques.

Main Results:

• The method provided reproducible estimates of average helical periodicity for DNA fragments.
• It allowed for the comparison of two DNA fragments.
• Helical repeat estimates for specific DNA inserts and methylation-induced helix unwindings were evaluated.

Conclusions:

• The electrophoretic mobility of DNA rings is a viable tool for measuring DNA helical twist.
• The method yields reproducible and accurate helical repeat estimates.
• It is applicable to various DNA sequences, inserts, and methylation states.