Weakly Bound Clusters of Biological Interest

Abstract

Contents 1. Introduction 3943 2. Experimental Techniques Available for the Study of Molecular Clusters 3945 2.1. IR Spectroscopy 3945 2.2. UV Spectroscopy 3946 2.3. Cluster Cations 3946 2.4. Cluster Anions 3946 2.5. Real-Time Monitoring of Solute−Solvent Interactions 3947 3. Problems Specific to the Study of Molecules of Biological Interest in the Gas Phase 3948 3.1. Production and Ionization of Molecules of Biological Interest in the Gas Phase 3949 3.2. Determination of Biomolecule Structures in the Gas Phase 3949 3.3. Microwave, Optical, and RET Spectroscopies of Molecular Clusters of Biological Interest in the Gas Phase 3950 4. Case Studies 3950 4.1. DNA Base Complexes 3950 4.1.1. Isolated Base Pairs 3951 4.1.2. Influence of Solvation upon Ionization Potentials and Electron Affinities of Nucleobases 3952 4.1.3. Proton Transfer and Tautomerization of Nucleobases and Related Molecular Systems 3953 4.2. Peptide Bonds and Amino Acid Side Chains 3953 4.2.1. Models of Peptide Bonds 3953 4.2.2. Models of Amino Acid Residues 3954 4.2.3. Disulfur Bonds 3954 4.2.4. Zwitterions 3954 4.3. Nucleobase−Amino Acid Residue Interactions 3955 4.4. Influence of Methylation 3956 4.5. Modeling of Hydrophobic Interactions 3957 4.6. Chiral Clusters 3957 5. Conclusion 3958 6. References 3959

Theoretical Modeling of Radiation‐Induced DNA Damage

“…34,[67][68][69][70][71][72][73] From theory and experiment, it is well known that all the bases (A, T, G, C, and U) have negative vertical electron affinity values in gas phase. 34,67,74,75 While all the bases have negative VEA, the adiabatic electron affinities (AEAs) of bases (C, T, and U) are found to be near zero [76][77][78] and still negative for A and G 34,74,79 (see Table 1.1). Under solvation, the radical anionic states of the bases become substantially stabilized and trap the excess electron, thereby preventing autodetachment.…”

Effects of Microsolvation on the Stability of Zwitterionic Valine

“…Effects of microsolvation on the structures and reactivity of amino acids, both canonical [1][2][3][4][5][6][7][8][9][10][11][12] and zwitterionic 10,[13][14][15][16][17][18][19][20] have been under intensive study to address the intriguing question of how many water molecules may stabilize the zwitterionic form of amino acids. Both theoretical and experimental studies carried out to examine the relative stability of the canonical and zwitterionic forms as a function of the number of microsolvating water molecules indicated that the effects of microsolvating water molecules depend highly on the structure of amino acids.…”

A Drude-model approach to dispersion interactions in dipole-bound anions

“…[41][42][43][44][45][46] In addition, many biologically important molecules can exist as zwitterions, which because of their large dipole moments, can form dipole-bound anions. [46][47][48][49][50] Dipole-bound anions have also been found to be important in charge-transfer processes. For example, photo-excitation of I -· (H 2 O) 4 leads to the charge transfer-complex I·(H 2 O) 4 -, with the excess electron bound to the cyclic (H 2 O) 4 cluster, distorted so that it has a large dipole moment.…”