Report on WG1 meeting: Electron and biomolecular interactions
Held at the Altis Park Hotel, Lisbon, Portugal 23 to 25 February 2006
Attendees | Aims and Objectives |
Talks | Mission Statement |
Report | Photographs
Local Host Meeting Secretary: Dr Paulo Limao-Vieira, Atomic and
Molecular Collisions Laboratory, Department of Physics, New University of
Lisbon, Portugal
In attendance (see also attendance sheets).
Working Group 1 members and invited experts
Jacqueline Bergès (University of Paris, France)
Stephan Denifl (University of Innsbruck, Austria)
David Field (University of Aarhus, Denmark). Chairman of WG1
Melvyn Folkard (Gray Cancer Institute, UK)
Gustavo Garcia (University of Madrid, Spain)
Jimena Gorfinkiel (Open University, UK)
Alexandre Giuliani (ICNS – CNRS, France)
Chantal Houée-Levin (university Paris XI, France)
Eugen Illenberger (Free University, Berlin, Germany)
Nykola Jones (University of Aarhus, Denmark)
Bratislav Marinkovic (University of Belgrade, Serbia,Yugoslavia)
Nigel Mason (Open University, UK)
Stefan Matejcik (Comenius University of Bratislava, Slovakia)
Paulo Limao-Vieira (New University of Lisbon, Portugal)
Jan Skalny (Comenius University of Bratislava, Slovakia)
Gosia Smialek (Open University, UK)
Marian Wolszczak (University of Lodz, Poland)
Local Staff and students (attending formal sessions).
Ana Fernandes (New University of Lisbon, Portugal)
Quirina Ferreira (New University of Lisbon, Portugal)
Paulo Gomes (New University of Lisbon, Portugal)
Joao Lourenço (New University of Lisbon, Portugal)
Victor Kokhan (New University of Lisbon, Portugal)
Manuel Maneira (New University of Lisbon, Portugal)
Augusto Moutinho (New University of Lisbon, Portugal)
Marta Nobre (New University of Lisbon, Portugal)
Maria Raposo (New University of Lisbon, Portugal)
Paulo Ribeiro (New University of Lisbon, Portugal)
Filipe Silva (New University of Lisbon, Portugal)
Aims and objectives
This was the second meeting of WG1 of this COST Action. The purpose of
this meeting was:
1) That each member of WG1, representing a team of scientists, should give
a seminar describing their work in the field of electron/UV interactions
with molecules, with special reference to processes of radiation damage.
2) That the Working group should discuss the achievements of the research
conducted by the WG members since the establishment of the WG1 in 2004 and
plan a future “Mission Statement” for WG1 2006-8.
3) That members would develop their existing collaborations and establish
new links via COST financed visits.
Report on the meeting
Talks
1) 13 talks were presented: Professor Illenberger
(Free University Berlin): “Electron driven reactions in biologically
relevant systems”, Professor Wolszczak (University of Lodz): "Experimental
Studies of Electron Transfer within DNA Helix", Professor Mason (Open
University): “UV and electron induced damage of DNA”, Professor
Houée-Lévin (Université Paris Sud): “Role of secondary structure on
radio-sensitivity of beta amyloid peptide”, Dr. Denifl (University of
Innsbruck): “Electron impact ionization and attachment studies of
biomolecules embedded in He droplets”, Dr. Giuliani (ICSN, France): "Mass
spectrometric study of atmospheric pressure VUV photoionisation of
peptides", Professor Garcia (CSIC - Madrid): “Low energy electron tracks
in ionisation chambers”, Professor Field (University of Aarhus): “First
experiments on the interaction of cold electrons with solids”, Dr. Bergès
(Universite Paris Sud): “QM/MM study of electron addition on protein
disulfide bonds”, Dr. Gorfinkiel (The Open University): “R-matrix
calculations for biologically relevant systems”, Dr. Matejcik (Comenius
University, Bratislava): “Electron attachment studies to selected
aminoacids”, Professor Ribeiro (New University of Lisbon): “Analysis of
biological structures by second harmonic generation” and Professor
Marinkovic (University of Belgrade): "Elastic and inelastic electron
scattering by biomolecules - the first step towards understanding of basic
interactions”. These presentations sparked lively discussion.
Mission Statement
2) A “Mission Statement” has been available for
WG1 since the start of the COST project. Although the mission statement
clearly remains a very good description of the aims of WG1 after due
discussion the WG decided to add a statement which makes clear that, at
this stage in the COST project, we would like to make a more clear
connection between radiation damage at the molecular level with clinical
practice. We should like to able to use our results to influence the
protocols that will in future be developed for heavy ion therapy, a
relatively new venture in medical practice and one in which several
laboratories in WG1 have plans (Gray Cancer Institute, Aarhus University).
In this connection we would like to see more meetings in the second half
of the COST project which involve members of other WGs. In our case we
intend to plan a joint meeting with WG2 whose theme is ions and
biomolecular interactions. Planning for this meeting will be made at the
main COST meeting in Groningen June 6-9th 2006.
Report
3). There follows a brief report on some of the
highlights and scientific discussions at the meeting.
The theme of WG1 is the experimental investigation of the interactions
of electrons and light with biomolecules and water. Experimental
investigations embrace a broad range of processes and studies of
dissociative events, electron transfer, electronic and vibrational
excitation, photon induced events and techniques of quantitative
assessment of damage.
Electron transfer in peptides and proteins is one of the major
processes for initiation and development of numerous diseases, triggering
of cellular death, and amplification of radiation damage. Chantal Houée-Levin
(Paris XI) reported studies the one-electron oxidation of beta amyloid
peptide and related peptides. Free radical oxidation of this peptide is
one of the prominent events in the course of Alzheimer's disease. It was
shown that secondary structure drives the process: if the peptide is
composed of beta sheets, methionine 35 is the target, if it is in alpha
helix form, methionine is not oxidized. Without any defined structure,
tyrosine 10 is mostly oxidized. Circular dichroism (CD) spectroscopy,
especially synchrotron radiation CD, was highlighted as an important tool
in these investigations. This is available at Daresbury Laboratory and at
Aarhus University. Some very interesting and insightful calculations were
reported by Jacqueline Bergès (Paris XI) on electron addition to protein
disulphide bonds, showing that the stability of the S-S bonds depends
strongly on the molecular conformation.
Jimena Gorfinkel (Open University) described how well established
theoretical methods are being applied to electron collisions with
biologically relevant molecules. The quality of the results is lower than
for small targets with only a few nuclei and less than 40 electrons, but
results are promising. Elastic and electronically inelastic cross-sections
as well as resonance parameters are calculated, but the analysis of the
dissociation products can, at present, only be performed qualitatively
Data for very low energy electron collisions with biomolecules (bases
and aminoacids) were reported from the Bratislava /Innsbruck groups
(Stephan Denifl, University of Innsbruck; Stefan Matejcik Comenius
University of Bratislava) showing the sensitivity of biomolecules to
electrons in the gas phase and in liquid helium droplets and the strong
dependence of electron energy associated with this. David Field (Aarhus)
showed data for very low energy electrons interacting with solid acetic
acid and with fluorobenzene, in the first tests of a new instrument now
functioning at Aarhus University. Data for rotational state to rotational
state transitions collisions in gas phase water induced by very cold
electrons were also shown. The significance or otherwise of dipole bound
states in electron collisions with highly polar biomolecules was discussed
and may have bearing on the interpretation of the data emerging from
Innsbruck, Bratislava and the Lincoln (Nebraska) laboratories.
Marian Wolszczak (University of Lodz, Poland) discussed photochemistry
of biomolecules. The most important conclusion of these studies is the
observation that the diffusion of the cationic species along the anionic
polyelectrolyte is severely restricted due to their electrostatic and/or
hydrophobic interactions with polymer. The transfer of the quencher
molecule from the trap (complex between quencher and monomer units of
polyelectrolyte in which both electrostatic and hydrophobic interactions
are involved) to excited probe can be regarded as a multistep diffusion
process with a single hopping event determined by the energy required for
quencher release from the trap. Results of our time-resolved studies
suggest that the DNA base pair stack is a poor medium for long-range
photoinduced electron transfer between intercalated donor and acceptor.
However DNA may facilitate electron transfer over short distances of three
or four interspersed base pairs. A relatively short distance of electron
transfer in DNA in solution from base radical anions to electron- affinic
intercalators (3 - 4 base pairs) is also found in the pulse radiolysis
studies. It can be due to competing protonation of certain base radical
anions.
Bratislav Marinkovic (University of Belgrade) and Eugen Illenberger
(Free University, Berlin, Germany) gave customarily lucid accounts of
electron-driven chemistry, including mention of electron driven breakage
of hydrogen bonds. Alexandre Giuliani (ICSN, France) treated higher energy
VUV photon interactions, whilst Nigel Mason confronted both electron
driven and photon driven damage in DNA, mentioning the pioneering work of
Gosia Smialek (present at the meeting) involving the use of AFM in
visualising strand breaks directly. Gustavo Garcia (Madrid) reported how
fundamental data collected in electron molecule interactions may be used
to model track damage. In a rather new field, Professor Ribeiro (New
University of Lisbon) described how one may, at least in principle,
analyse the properties of biomolecules through non-linear optical effects
and second harmonic generation.
The brief of WG1 is to continue the studies outlined above and other
studies to build up a body of knowledge on which to base realistic models
of electron and photon-induced damage in biological cells. As mentioned
above, WG1 is keen on complementary information and interlinking with the
other working groups, concerned for example with the effects of ions on
biomolecules and the extension into true physiological environments,
including track structure in cells. It was also stressed by Nigel Mason
and others that an important product of our work is an understanding of
the chemical activation of biomolecules on surfaces. Some of the data
which we produce are likely to be fundamental to fabrication in
bionanotechnology. A number of members were clearly very interested in
arranging mutual visits.
In summary, there was a strong feeling that this was a very useful and
fruitful contact at the scientific level among workers from a number of
different backgrounds, spanning those with strong medical interests (Gray
Cancer Institute and CSIC, Madrid), via those who work in radiation
chemistry in the aqueous phase (Paris XI) to those who have up to the
present dealt with electron collisions largely in the gas phase (several
of the groups present).
The Next WG1 meeting will be arranged in 2007 at a venue as yet
undetermined. The WG was keen that this meeting will involve discussions
of the applications of the work and thus involve clinicians and
radiologists.
Dr Paulo Limao-Vieira
March 4 2006
Photographs
To view a larger version of the photograph, click on the image.
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The members of
COST P9 Working Group 1 |
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Attendees | Aims and Objectives |
Talks | Mission Statement |
Report
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