Single DNA Condensation Induced by Hexammine Cobalt with Molecular Combing |
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Authors: | Gao-ming Hu Yu Lin Shi-yong Ran Yan-wei Wang Guang-can Yang |
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Institution: | College of Physics and Electronic Information Engineering, Wenzhou University, Wenzhou 325035, China |
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Abstract: | We investigated the interaction between DNA and hexammine cobalt III Co(NH3)6]3+ by a simple molecular combing method and dynamic light scattering. The average extension of ?λ-DNA-YOYO-1 complex is found to be 20.9 μm, about 30% longer than the contour length of the DNA in TE buffer (10 mmol/L Tris, 1 mmol/L EDTA, pH=8.0), due to bis-intercalation of YOYO-1. A multivalent cation, hexammine cobalt, is used for DNA condensation. We find that the length of DNA-Co(NH3)6]3+ complexes decrease from 20.9 μm to 5.9 μm as the concentration of the Co(NH3)6]3+ vary from 0 to 3 μmol/L. This observation provides a direct visualization of single DNA condensation induced by hexammine cobalt. The results from the molecular combing studies are supported by dynamic light scattering investigation, where the average hydrodynamic radius of the DNA complex decreases from 203.8 nm to 39.26 nm under the same conditions. It shows that the molecular combing method is feasible for quantitative conformation characterization of single bio-macromolecules. |
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Keywords: | Molecular combing Hexammine cobalt Condensation Dynamic light scatter-ing Fluorescent microscopy |
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