calculations, which are in very good agreement with the experimental data, have
given the conceptual framework needed to rationalise the results.
These protonated aromatic amino acids are probably the molecules that have
the most complete experimental description. Indeed, for dynamics of neutral
molecules of this size the processes after internal conversion are totally
unknown, the branching ratio between different fragmentation channels are not
known and are very difficult to obtain and no study has ever reached the
temporal scale needed to properly describe the processes.
The general picture obtained for the protonated aromatic amino acids seems
to be useful for understanding the photo-fragmentation of small peptides
containing aromatic residues, but a complete understanding of the processes in
larger peptides is still lacking. The present results are opening a fascinating
possibility using lasers, changing their energy and time, to selectively break a
bond in proteins which have a given sequence or secondary structure. This may
lead to a kind of laser controlled therapy!
References
1. Lakowicz, J.R.: Invited review on spectral relaxation in proteins. Photochem. Photobiol. 72,
421–437 (2000)
2. Lakowicz, J.R.: Principles of Fluorescence Spectroscopy, 2nd edn. Springer, New York (1999)
3. Schermann, J.-P.: Spectroscopy and Modelling of Biomolecular Building Blocks. Elsevier,
Amsterdam (2008)
4. Katarzyna, G., Szabelsk, M., Rzeska, A., Karolczak, J., Sulowska, H., Wiesław, W.:
Photophysical properties of tyrosine at low pH range. Chem. Phys. Lett. 362, 519–526 (2002)
5. Philips, L.A., Webb, S.P., Martinez, S.J., Fleming, G.R., Levy, D.H.: Time-resolved spectroscopy of tryptophan conformers in a supersonic jet. J. Am. Chem. Soc. 110, 1352–1355 (1988)
6. Robbins, R.J., Fleming, G.R., Beddard, G.S., Robinson, G.W., Thistlethwaite, P.J., Woolfe, G.
J.: Photophysics of aqueous tryptophan: pH and temperature effects. J. Am. Chem. Soc. 102,
6271–6279 (1980)
7. Vivian, J.T., Callis, P.R.: Mechanisms of tryptophan fluorescence shifts in proteins. Biophys. J.
80, 2093–2109 (2001)
8. Callis, P.R., Petrenko, A., Muin, P.L., Tusell, J.R.: Ab initio prediction of tryptophan fluorescence quenching by protein electric field enabled electron transfer. J. Phys. Chem. B 111,
10335–10339 (2007)
9. Dedonder-Lardeux, C., Jouvet, C., Perun, S., Sobolewski, A.L.: External electric field effect on
the lowest excited states of indole: ab initio and molecular dynamics study. Phys. Chem.
Chem. Phys. 5, 5118–5127 (2003)
10. Marquezin, A., Hirata, I.Y., Juliano, L., Ito, A.S.: Tryptophan as a probe for acid–base
equilibria in peptides. Biopolymers 71, 569–576 (2003)
11. Rizzo, T.R., Park, Y.D., Peteanu, L.A., Levy, D.H.: The electronic spectrum of the amino acid
tryptophan in the gas phase. J. Chem. Phys. 84, 2534–2541 (1986)
12. Inokuchi, Y., Kobayashi, Y., Ito, T., Ebata, T.: Conformation of L-tyrosine studied by
fluorescence-detected UV-UV and IR-UV double-resonance spectroscopy. J. Phys. Chem. A
111, 3209–3215 (2007)
13. Hu ¨nig, I., Seefeld, K.A., Kleinermanns, K.: REMPI and UV–UV double resonance spectroscopy of tryptophan ethylester and the dipeptides tryptophan–serine, glycine–tryptophan and
proline–tryptophan. Chem. Phys. Lett. 369, 173–179 (2003)
9 Excited-State Dynamics of Protonated Aromatic Amino Acids
177
given the conceptual framework needed to rationalise the results.
These protonated aromatic amino acids are probably the molecules that have
the most complete experimental description. Indeed, for dynamics of neutral
molecules of this size the processes after internal conversion are totally
unknown, the branching ratio between different fragmentation channels are not
known and are very difficult to obtain and no study has ever reached the
temporal scale needed to properly describe the processes.
The general picture obtained for the protonated aromatic amino acids seems
to be useful for understanding the photo-fragmentation of small peptides
containing aromatic residues, but a complete understanding of the processes in
larger peptides is still lacking. The present results are opening a fascinating
possibility using lasers, changing their energy and time, to selectively break a
bond in proteins which have a given sequence or secondary structure. This may
lead to a kind of laser controlled therapy!
References
1. Lakowicz, J.R.: Invited review on spectral relaxation in proteins. Photochem. Photobiol. 72,
421–437 (2000)
2. Lakowicz, J.R.: Principles of Fluorescence Spectroscopy, 2nd edn. Springer, New York (1999)
3. Schermann, J.-P.: Spectroscopy and Modelling of Biomolecular Building Blocks. Elsevier,
Amsterdam (2008)
4. Katarzyna, G., Szabelsk, M., Rzeska, A., Karolczak, J., Sulowska, H., Wiesław, W.:
Photophysical properties of tyrosine at low pH range. Chem. Phys. Lett. 362, 519–526 (2002)
5. Philips, L.A., Webb, S.P., Martinez, S.J., Fleming, G.R., Levy, D.H.: Time-resolved spectroscopy of tryptophan conformers in a supersonic jet. J. Am. Chem. Soc. 110, 1352–1355 (1988)
6. Robbins, R.J., Fleming, G.R., Beddard, G.S., Robinson, G.W., Thistlethwaite, P.J., Woolfe, G.
J.: Photophysics of aqueous tryptophan: pH and temperature effects. J. Am. Chem. Soc. 102,
6271–6279 (1980)
7. Vivian, J.T., Callis, P.R.: Mechanisms of tryptophan fluorescence shifts in proteins. Biophys. J.
80, 2093–2109 (2001)
8. Callis, P.R., Petrenko, A., Muin, P.L., Tusell, J.R.: Ab initio prediction of tryptophan fluorescence quenching by protein electric field enabled electron transfer. J. Phys. Chem. B 111,
10335–10339 (2007)
9. Dedonder-Lardeux, C., Jouvet, C., Perun, S., Sobolewski, A.L.: External electric field effect on
the lowest excited states of indole: ab initio and molecular dynamics study. Phys. Chem.
Chem. Phys. 5, 5118–5127 (2003)
10. Marquezin, A., Hirata, I.Y., Juliano, L., Ito, A.S.: Tryptophan as a probe for acid–base
equilibria in peptides. Biopolymers 71, 569–576 (2003)
11. Rizzo, T.R., Park, Y.D., Peteanu, L.A., Levy, D.H.: The electronic spectrum of the amino acid
tryptophan in the gas phase. J. Chem. Phys. 84, 2534–2541 (1986)
12. Inokuchi, Y., Kobayashi, Y., Ito, T., Ebata, T.: Conformation of L-tyrosine studied by
fluorescence-detected UV-UV and IR-UV double-resonance spectroscopy. J. Phys. Chem. A
111, 3209–3215 (2007)
13. Hu ¨nig, I., Seefeld, K.A., Kleinermanns, K.: REMPI and UV–UV double resonance spectroscopy of tryptophan ethylester and the dipeptides tryptophan–serine, glycine–tryptophan and
proline–tryptophan. Chem. Phys. Lett. 369, 173–179 (2003)
9 Excited-State Dynamics of Protonated Aromatic Amino Acids
177