VACUUM ULTRAVIOLET CIRCULAR DICHROISM OF DOUBLE STRANDED NUCLEIC ACIDS |
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| Authors: | John C.,Sutherland ,Bohai,Lin &dagger ,Jo Ann, Mugavero ,John,Trunk ,Maria,Tomasz ,Regina,Santella ,Luis,Marky Kenneth J.,Breslauer |
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| Affiliation: | Biology Department, Brookhaven National Laboratory, Upton, NY 11973;Department of Chemistry, Hunter College, City University of New York, New York, NY 10021;Institute of Cancer Research, Columbia University, New York, NY 10032;Department of Chemistry, Rutgers University, New Brunswick, NJ 08903, USA |
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| Abstract: | The vacuum ultraviolet (VUV) circular dichroism (CD) of double stranded DNA and RNA is greater in amplitude than the CD of these molecules for wavelengths longer than 200 nm. The amplitude of the VUV-CD depends on the base composition of DNA, with guanine-cytosine base pairs contributing more intensity than adenine-thymine base pairs. The shape and amplitude of the VUV-CO are better indicators of nucleic acid conformation (A, B or Z) than are those of the longer wavelength CD. We illustrate the unique features of VUV-CD with specific examples. In the presence of Cs+ and ethanol, VUV-CD reveals that poly(dA-dC)poly(dG-dT) forms a right handed double helix despite the inversion of the longer wavelength CD, which usually is used as a benchmark for the left-handed form. The greater magnitude of the VUV-CD of DNA and RNA compared to longer wavelengths means that the VUV-CD is less susceptible to distortion by the induced CD of UV-absorbing ligands like mitomycin C and N-2-acetylaminofluorene. |
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