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Relaxation methods

Relaxation methods. A chemical equilibrium is thrown off-balance, and we measure the rate of reaching the new equilibrium. E.g.: temperature jump,. Revival of the temperature jump method. Measurement of the rate of protein folding:.

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Relaxation methods

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  1. Relaxation methods A chemical equilibrium is thrown off-balance, and we measure the rate of reaching the new equilibrium. E.g.: temperature jump,

  2. Revival of the temperature jump method Measurement of the rate of protein folding: The fluorescence of tryptophane (ns time-scale) is influenced by the polarity of the medium. Protein folding tends to exclude water from the globule. Principle of the measurement: the protein is defolded by cooling, then a temperature jump returns the temperature to physiological conditions. The tryptophane fluorescence is measured on the ms timescale, thus we can follow the change of polarity near the tryptophane.

  3. Time-correlated single photon counting Instead of measuring the decay of fluorescence in real time, we measure the time between the excitation and emission, and based on the statistics we estimate the lifetime of the fluorescence.

  4. Photochemistry of the >C=C< chromophore: cis – transphotoisomerization

  5. Photostationary state cis  trans Stilbene (1,2-diphenylethane), 313 nm: 93%cis, 7% trans, since ecis 2400 dm3mol-1s-1, etrans 16200 dm3mol-1s-1, Fct = 0,35, Ftc = 0,5

  6. Additive colours

  7. Substractive colours

  8. How the human eye works

  9. Electrocyclization

  10. Practical example: synthesis of vitamin D

  11. Stereochemistry of cycloaddition

  12. Cycloaddition within DNA

  13. Relativeweight of DNA photodamage

  14. Photochemistry of proteins

  15. Correlationbetweenenzymephotoinactivation and cystinecontent

  16. Spectrum of the main photoproductinthelens

  17. Thephoto-chemistryof beer:thiolproductioninduced by light

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