1 / 14

Solar UV Radiation

Solar UV Radiation. UVC <290 nm Absorbed by ozone UVB 290 – 320 nm ~0.5 % total energy UVA 320 – 400 nm 6% total energy. UV Spectrum of DNA. Absorbance. 300. 250. Wavelength (nm). T<>T. T<>C. C<>C. Pyrimidine Photodimers. Bipyrimidine (6-4) Photoadducts.

arden-glenn
Download Presentation

Solar UV Radiation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Solar UV Radiation • UVC <290 nm Absorbed by ozone • UVB 290 – 320 nm ~0.5 % total energy • UVA 320 – 400 nm 6% total energy

  2. UV Spectrum of DNA Absorbance 300 250 Wavelength (nm)

  3. T<>T T<>C C<>C Pyrimidine Photodimers

  4. Bipyrimidine (6-4) Photoadducts

  5. DNA Photooxidation Mechanisms Oxidation at GG(A) doublet P G Oxidation hν Hole Transfer DNA Type I Type II P-.+ DNA+. P* 1O2 singlet oxygen O2 DNA

  6. Method of irradiation and visualization of DNA damage UV irradiation 32P-DNA + PS Upturned Eppendorf lid EtOH precipitation  Piperidine Electrophoresis Autoradiography

  7. Single-stranded DNA • Singlet oxygen • UV dose & [SP] dependent Uniform G-specific attack

  8. Quenching in ssDNA 1SP + UVB 2 & 3Quenched by sodium azide & DABCO 4 & 5Mannitol & SOD have no effect

  9. H2O D2O Singlet oxygen damage in ss DNA increases in D2O

  10. Duplex DNA Specificity for 5’-G of 5’-GG-3’ doublets 5’-G of 5’-GA-3’ doublets

  11. Conclusions • Single-stranded DNA - Type II mechanism • singlet oxygen • Duplex DNA - Type I mechanism • electron transfer - DNA to excited sensitizer • hole migration

  12. MALDI-TOF Analysis of DNA • Requires picomole amounts of sample • Mass accuracy to ~0.1% • Generate +ve and –ve ion spectra • UV-absorbing matrix for <100 base pairs • Applications in DNA sequencing

More Related