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Lecture 2 Application of optical tweezers in single-molecule experiments with DNA

Lecture 2 Application of optical tweezers in single-molecule experiments with DNA. Entropic elasticity of a single DNA molecule. DNA and RNA stretching experiments. First experiment by Carlos Bustamante and co-workers Science (1992). Nucleotides Adenine, Guanine, Cytosine, Tymine. A ... T

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Lecture 2 Application of optical tweezers in single-molecule experiments with DNA

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  1. Lecture 2 Application of optical tweezers in single-molecule experiments with DNA Entropic elasticity of a single DNA molecule DNA and RNA stretching experiments First experiment byCarlos Bustamante and co-workers Science (1992) Nucleotides Adenine, Guanine, Cytosine, Tymine A ... T G ... C C ... G T ... A . . .

  2. Optical Tweezers A. Ashkin, Phys. Rev. Lett. 24, 156 (1970) Recent theoretical and experimental advances Mazolli, Maia Neto, and Nussenzveig, Proc. R. Soc. London, Ser. A 459, 3021 (2003) Viana, Rocha, Mesquita, Mazolli, Maia Neto, Nussenzveig, Appl. Phys. Lett. (2006) and PRE (2007) Neves, Fontes, Pozzo, Thomaz, Chilce, Rodriguez, Barbosa, Lenz-Cesar, Optics Express (2006)

  3. Visible He-Ne back-scattering profile

  4. Force x extension curve Marko-Siggia equation S. Harris et al. BJ 2005 (large scale MD, entropic effects, denaturing bubbles); G. Weber et al. Nature Phys., 2009 (microscopic elasticity). z= end-to-end distance A= persistence length L= contour length

  5. DNA/Ethidium Bromide Fit to the neighbor exclusion model

  6. Ethidium bromide Daunomycin M. S. Rocha et al. JPC 2007

  7. Psoralen

  8. Psoralen Circles: intercalated Squares: intercalated + UVA light Márcio. S. Rocha, doctoral thesis UFMG (2008)

  9. Psoralen intercalated fraction neighbor exclusion model Persistence length abrupt transition around r ~ 0.4

  10. ab initio DFTcalculation DNA/Psoralen r = concentration of drug bound/concentration of DNA base-pairs r=0.4 r=0.5

  11. ab initio DFTcalculation DNA/Psoralen “DNA-psoralen: single-molecule experiments and first principles calculations” M. S. Rocha, A. D. Lúcio, S. S. Alexandre, R. W. Nunes, and O. N. Mesquita (APL, 2009)

  12. Water transport in a single MDCK kidney cell How to measure the volume of a cell?

  13. MDCK Kidney Cell Isoosmotic medium Hiperosmotic medium

  14. Osmoregulation

  15. Effect of vasopressin (AVP) on water transport Lucio, Santos, and Mesquita, PRE (2003)

  16. Stretching DNA

  17. Stretching RNA

  18. The 3 Main Classes of Motor Proteins

  19. DNA condensation

  20. PRL, 050601 (2002) Fluctuation theorem

  21. MORPHOLOGY-DEPENDENT RESONANCES (MDR) MODES

  22. Blood 92, 2975 (1998)

  23. PRL 93, 078102 (2004)

  24. Acustooptical deflectors

  25. Optical Tweezers is a very convenient tool to manipulate, apply and measure forces on single molecules (pN range). It can be used to measure and change transition states during protein folding, with access to the time evolution of these processes. • It can be used for manipulating single cells for measurements of membrane elasticity, water transport and for manipulation of organelles inside the cell. • It has been used as an interesting tool to test new ideas on Statistical Physics of small systems. • It has been used for manipulation of nanowires, carbon nanotubes and silver nanoparticles. • Applications of optical tweezers have increased much during the last few years.

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