Low energy electron-driven damage in biomolecules
TL;DR: By comparing the results from different experiments and theory, it is possible to determine fundamental mechanisms that are involved in the dissociation of the biomolecules and the production of single- and double-strand breaks in DNA.
Abstract: The damage induced by the impact of low energy electrons (LEE) on
biomolecules is reviewed from a radiobiological perspective with emphasis on
transient anion formation. The major type of experiments, which measure the
yields of fragments produced as a function of incident electron energy
(0.1-30 eV), are briefly described. Theoretical advances are also
summarized. Several examples are presented from the results of recent
experiments performed in the gas-phase and on biomolecular films bombarded
with LEE under ultra-high vacuum conditions. These include the results
obtained from DNA films and those obtained from the fragmentation of
elementary components of the DNA molecule (i.e., the bases, sugar and
phosphate group analogs and oligonucleotides) and of proteins (e.g. amino
acids). By comparing the results from different experiments and theory, it
is possible to determine fundamental mechanisms that are involved in the
dissociation of the biomolecules and the production of single- and
double-strand breaks in DNA. Below 15 eV, electron resonances (i.e., the
formation of transient anions) play a dominant role in the fragmentation of
all biomolecules investigated. These transient anions fragment molecules by
decaying into dissociative electronically excited states or by dissociating
into a stable anion and a neutral radical. These fragments can initiate
further reactions within large biomolecules or with nearby molecules and
thus cause more complex chemical damage. Dissociation of a transient anion
within DNA may occur by direct electron attachment at the location of
dissociation or by electron transfer from another subunit. Damage to DNA is
dependent on the molecular environment, topology, type of counter ion,
sequence context and chemical modifications.
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TL;DR: The current understanding of the fundamental mechanisms involved in LEE-induced damage of DNA and complex biomolecule films is summarized and the potential of controlling this damage using molecular and nanoparticle targets with high LEE yields in targeted radiation-based cancer therapies is discussed.
Abstract: Many experimental and theoretical advances have recently allowed the study of direct and indirect effects of low-energy electrons (LEEs) on DNA damage. In an effort to explain how LEEs damage the human genome, researchers have focused efforts on LEE interactions with bacterial plasmids, DNA bases, sugar analogs, phosphate groups, and longer DNA moieties. Here, we summarize the current understanding of the fundamental mechanisms involved in LEE-induced damage of DNA and complex biomolecule films. Results obtained by several laboratories on films prepared and analyzed by different methods and irradiated with different electron-beam current densities and fluencies are presented. Despite varied conditions (e.g., film thicknesses and morphologies, intrinsic water content, substrate interactions, and extrinsic atmospheric compositions), comparisons show a striking resemblance in the types of damage produced and their yield functions. The potential of controlling this damage using molecular and nanoparticle targets with high LEE yields in targeted radiation-based cancer therapies is also discussed.
326 citations
TL;DR: The mechanism of strand break formation by low-energy electrons involves an interesting through-bond electron-transfer process as discussed by the authors, which is the mechanism by which very low energy free electrons attach to DNA and cause strong (ca. 4 eV) covalent bonds to break causing so-called single-strand breaks.
Abstract: We overview our recent theoretical predictions and the innovative experimental findings that inspired us concerning the mechanisms by which very low-energy (0.1-2 eV) free electrons attach to DNA and cause strong (ca. 4 eV) covalent bonds to break causing so-called single-strand breaks. Our primary conclusions are that (i) attachment of electrons in the above energy range to base pi* orbitals is more likely than attachment elsewhere and (ii) attachment to base pi* orbitals most likely results in cleavage of sugar-phosphate C-O sigma bonds. Later experimental findings that confirmed our predictions about the nature of the electron attachment event and about which bonds break when strand breaks form are also discussed. The proposed mechanism of strand break formation by low-energy electrons involves an interesting through-bond electron-transfer process.
309 citations
TL;DR: In this article, the major findings which have been consolidated from a broad variety of existing experiments and, at the same time, the main computational approaches which describe the extent of molecular damage following the initial electron attachment process are presented.
263 citations
TL;DR: In this article, a review of low-energy electron-induced reactions in nanoscale thin adsorbates is presented, which can provide insights into the chemistry of high energy radiation-induced chemical reactions in condensed matter.
225 citations
TL;DR: Time-resolved photoelectron spectroscopy reveals that, althoughadenine and 9-methyl adenine show almost identical timescales for the processes involved, the decay pathways are quite different and it is confirmed that in adanine at 267-nm excitation, the πσ* state plays a major role.
Abstract: The UV chromophores in DNA are the nucleic bases themselves, and it is their photophysics and photochemistry that govern the intrinsic photostability of DNA. Because stability is related to the conversion of dangerous electronic to less-dangerous vibrational energy, we study ultrafast electronic relaxation processes in the DNA base adenine. We excite adenine, isolated in a molecular beam, to its ππ* state and follow its relaxation dynamics using femtosecond time-resolved photoelectron spectroscopy. To discern which processes are important on which timescales, we compare adenine with 9-methyl adenine. Methylation blocks the site of the much-discussed πσ* state that had been thought, until now, minor. Time-resolved photoelectron spectroscopy reveals that, although adenine and 9-methyl adenine show almost identical timescales for the processes involved, the decay pathways are quite different. Importantly, we confirm that in adenine at 267-nm excitation, the πσ* state plays a major role. We discuss these results in the context of recent experimental and theoretical studies on adenine, proposing a model that accounts for all known results, and consider the relationship between these studies and electron-induced damage in DNA.
190 citations
References
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Book•
15 Jan 2001
TL;DR: Molecular Cloning has served as the foundation of technical expertise in labs worldwide for 30 years as mentioned in this paper and has been so popular, or so influential, that no other manual has been more widely used and influential.
Abstract: Molecular Cloning has served as the foundation of technical expertise in labs worldwide for 30 years. No other manual has been so popular, or so influential. Molecular Cloning, Fourth Edition, by the celebrated founding author Joe Sambrook and new co-author, the distinguished HHMI investigator Michael Green, preserves the highly praised detail and clarity of previous editions and includes specific chapters and protocols commissioned for the book from expert practitioners at Yale, U Mass, Rockefeller University, Texas Tech, Cold Spring Harbor Laboratory, Washington University, and other leading institutions. The theoretical and historical underpinnings of techniques are prominent features of the presentation throughout, information that does much to help trouble-shoot experimental problems. For the fourth edition of this classic work, the content has been entirely recast to include nucleic-acid based methods selected as the most widely used and valuable in molecular and cellular biology laboratories. Core chapters from the third edition have been revised to feature current strategies and approaches to the preparation and cloning of nucleic acids, gene transfer, and expression analysis. They are augmented by 12 new chapters which show how DNA, RNA, and proteins should be prepared, evaluated, and manipulated, and how data generation and analysis can be handled. The new content includes methods for studying interactions between cellular components, such as microarrays, next-generation sequencing technologies, RNA interference, and epigenetic analysis using DNA methylation techniques and chromatin immunoprecipitation. To make sense of the wealth of data produced by these techniques, a bioinformatics chapter describes the use of analytical tools for comparing sequences of genes and proteins and identifying common expression patterns among sets of genes. Building on thirty years of trust, reliability, and authority, the fourth edition of Mol
215,169 citations
Book•
01 Jan 2001
TL;DR: The content has been entirely recast to include nucleic-acid based methods selected as the most widely used and valuable in molecular and cellular biology laboratories.
Abstract: Molecular Cloning has served as the foundation of technical expertise in labs worldwide for 30 years. No other manual has been so popular, or so influential. Molecular Cloning, Fourth Edition, by the celebrated founding author Joe Sambrook and new co-author, the distinguished HHMI investigator Michael Green, preserves the highly praised detail and clarity of previous editions and includes specific chapters and protocols commissioned for the book from expert practitioners at Yale, U Mass, Rockefeller University, Texas Tech, Cold Spring Harbor Laboratory, Washington University, and other leading institutions. The theoretical and historical underpinnings of techniques are prominent features of the presentation throughout, information that does much to help trouble-shoot experimental problems. For the fourth edition of this classic work, the content has been entirely recast to include nucleic-acid based methods selected as the most widely used and valuable in molecular and cellular biology laboratories. Core chapters from the third edition have been revised to feature current strategies and approaches to the preparation and cloning of nucleic acids, gene transfer, and expression analysis. They are augmented by 12 new chapters which show how DNA, RNA, and proteins should be prepared, evaluated, and manipulated, and how data generation and analysis can be handled. The new content includes methods for studying interactions between cellular components, such as microarrays, next-generation sequencing technologies, RNA interference, and epigenetic analysis using DNA methylation techniques and chromatin immunoprecipitation. To make sense of the wealth of data produced by these techniques, a bioinformatics chapter describes the use of analytical tools for comparing sequences of genes and proteins and identifying common expression patterns among sets of genes. Building on thirty years of trust, reliability, and authority, the fourth edition of Mol
25,596 citations
01 Jan 1989
6,457 citations
"Low energy electron-driven damage i..." refers methods in this paper
...The resulting solution can then be analyzed by various standard chemical methods of analysis [71,72]....
[...]
...If analysis in vacuo is not possible, in principle, one could recuperate and analyze outside vacuum the products remaining on the surface by chemical methods, such as electrophoresis [71], chromatography, gas and liquid chromatography, gas chromatography/mass spectrometry (GC/MS), liquid chromatography/MS (LC/MS) [72] or hybridization with complementary strands in the case of oligonucleotides [73]....
[...]
3,009 citations
Book•
01 Jan 1949
TL;DR: The perturbation theory has been applied to many-body problems and applications, such as electron collisions with atoms, collisions between atomic systems, nuclear collisions, and certain aspects of two-body systems under relativistic collisions.
Abstract: Volume II of this work covers many-body problems and applications of the theory to electron collisions with atoms, collisions between atomic systems, nuclear collisions, certain aspects of two-body systems under relativistic collisions, and the use of time-dependent perturbation theory. Despite the amount of work carried out since this book was first published, the underlying theory presented here remains both sound and of practical value to all theoretical physicists.
2,969 citations