Physical Characteristics of DAP DNA Open Access

Jeon, Hamin (2013)

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The flexibility and torsional stiffness of DNA can influence important biological processes including nucleosome formation and DNA wrapping. To study the significance of these DNA properties, we characterized the effects of tension and torsion on 2,6 diaminopurine substituted DNA (DAP DNA) by using magnetic tweezers (MTs). By obtaining plots of DNA extension as a function of torsion applied to the DNA under different tensions, the helical repeat of DAP DNA in left-handed form and the relative extension of DAP DNA in left-handed form to right-handed form were computed. Force vs. extension curves of DAP DNA under different amounts of torsion were also plotted, and used to calculate the torsional constant, 62.0 ± 21.6 nm, and critical torque, 3.73×10-21 N×m of DAP DNA. The computed critical torque value was different from the value reported in the literature3 for normal DNA.

Table of Contents

Table of Contents

1. Introduction...1

1.1 Motivation...1

1.2 DNA Supercoiling...1

1.3 Magnetic Tweezers...2

1.4 DAP DNA...3

2. Methods...6

2.1 Preparation of DAP DNA...6

2.2 Preparation of a Flow Chamber...7

2.3 Magnetic Tweezers Experiment...9

3. Results and Discussion...12

4. Conclusion...20


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