COMPUTER MODELS OF THE AGS, I : The D. C. Bare Machine at High Fields

Auerbach, E.

doi:10.2172/1151205

Cited by 5 publications

(5 citation statements)

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“…Cells from FA patients are particularly sensitive to DNA cross-linking agents such as mitomycin C (MMC) (3) and diepoxybutane (4), suggestive of defects in a pathway that normally promotes genomic stability by responding to cross-link damage. FA is a genetically heterogeneous disorder for which at least 12 complementation groups (A, B, C, D1, D2, E, F, G, I, J, L, and M) have been identified to date.…”

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confidence: 99%

Structural Determinants of Human FANCF Protein That Function in the Assembly of a DNA Damage Signaling Complex

Kowal

Gurtan

Stuckert

et al. 2007

Journal of Biological Chemistry

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Fanconi anemia (FA) is a rare autosomal recessive and X-linked chromosomal instability disorder. At least eight FA proteins (FANCA, B, C, E, F, G, L, and M) form a nuclear core complex required for monoubiquitination of a downstream protein, FANCD2. The human FANCF protein reportedly functions as a molecular adaptor within the FA nuclear complex, bridging between the subcomplexes A:G and C:E. Our x-ray crystallographic studies of the C-terminal domain of FANCF reveal a helical repeat structure similar to the Cand1 regulator of the Cul1-Rbx1-Skp1-Fbox Skp2 ubiquitin ligase complex. Two C-terminal loops of FANCF are essential for monoubiquitination of FANCD2 and normal cellular resistance to the DNA cross-linking agent mitomycin C. FANCF mutants bearing amino acid substitutions in this C-terminal surface fail to interact with other components of the FA complex, indicating that this surface is critical for the proper assembly of the FA core complex.Fanconi anemia (FA) 3 is an inherited chromosomal instability disorder manifesting a variety of congenital malformations, pancytopenia, and a predisposition to cancer (1, 2). Cells from FA patients are particularly sensitive to DNA cross-linking agents such as mitomycin C (MMC) (3) and diepoxybutane (4), suggestive of defects in a pathway that normally promotes genomic stability by responding to cross-link damage. FA is a genetically heterogeneous disorder for which at least 12 complementation groups (A, B, C, D1, D2, E, F, G, I, J, L, and M) have been identified to date. Genes defective in 11 of the complementation groups have been cloned and shown to cooperate in a common biochemical pathway (5-14). FANCA, B, C, E, F, G, L, and M (11, 14 -18) form a putative E3 ubiquitin ligase core complex in the nucleus. The integrity of the core complex is essential for the monoubiquitination of FANCD2 (19) during the S-phase of the cell cycle (20) as well as for the upsurge of FANCD2 monoubiquitination following DNA damage by cross-linking agents, ultraviolet or ionizing radiation, and hydroxyurea-induced nucleotide depletion (19,21). The recently discovered FA-I complementation group has a defect in FANCD2 monoubiquitination with no apparent effect on the FA core complex (22), suggestive of additional complexity in the FA damage response pathway. Following exposure to DNAdamaging agents, monoubiquitinated FANCD2 moves into the chromatin fraction where it may function in repairing DNA damage by homologous recombination (23-25).Only three subunits of the FA core complex include regions of homology to proteins of known function or structure. FANCL possesses an N-terminal WD40 repeat region that mediates interactions with the FA complex (58) and a C-terminal plant homeodomain finger domain required for E3 ubiquitin ligase activity (11). The human FANCM protein is an ortholog of the archaeabacterial helicase-associated endonuclease for fork-structured DNA and contains both DNA helicase-like and endonuclease-like domains (14), suggesting a direct role for the FA core complex in the pr...

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confidence: 99%

Structural Determinants of Human FANCF Protein That Function in the Assembly of a DNA Damage Signaling Complex

Kowal

Gurtan

Stuckert

et al. 2007

Journal of Biological Chemistry

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“…Velocity profiles of photodesorbed atoms are determined by integrating the Br-atom yield as a function of the delay between excitation and probe lasers. Velocity profiles are converted to kinetic energy distributions by applying a Jacobian transformation . Each data point represents an average of the integrated mass selected ion signal from 60 laser pulses.…”

Section: Methodsmentioning

confidence: 99%

Photoinduced Br Desorption from CsBr Thin Films Grown on Cu(100)

et al. 2015

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Thin films of CsBr deposited onto metals such as copper are potential photocathode materials for light sources and other applications. We investigate desorption dynamics of Br atoms from CsBr films grown on insulator (KBr, LiF) and metal (Cu) substrates induced by sub-bandgap 6.4 eV laser pulses. The experimental results demonstrate that the peak kinetic energy of Br atoms desorbed from CsBr/Cu films is much lower than that for the hyperthermal desorption from CsBr/LiF films. Kelvin probe measurements indicate negative charge at the surface following Br desorption from CsBr/Cu films. Our ab initio calculations of excitons at CsBr surfaces demonstrate that this behavior can be explained by an exciton model of desorption including electron trapping at the CsBr surface. Trapped negative charges reduce the energy of surface excitons available for Br desorption. We examine the electron-trapping characteristics of low-coordinated sites at the surface, in particular, divacancies and kink sites. We also provide a model of cation desorption caused by Franck-Hertz excitation of F centers at the surface in the course of irradiation of CsBr/Cu films. These results provide new insights into the mechanisms of photoinduced structural evolution of alkali halide films on metal substrates and activation of metal photocathodes coated with CsBr.

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“…The solid curve through the data points of Figure is obtained by fitting the experimental data points to the velocity distribution for a collimated supersonic beam, − f false( v false) = N v 3 .25em exp ( − m false( v − u̅ false) 2 2 k T ) where T is the local temperature, u̅ is the average parallel velocity component of the ions within the expansion, N is a normalization constant such that the integral of the function over all space equals unity, and m is the weighted mass of the carrier gas (estimated to be 97% helium +3% butanone vapor). The only variable parameter in eq is the local temperature, T , which optimizes at values less than a single Kelvin.…”

Section: Methodsmentioning

confidence: 99%

Reaction Rate Constants and Mechanistic Detail of the Ni⁺+ Butanone Reaction

et al. 2011

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The unimolecular decomposition kinetics of the jet-cooled Ni(+)-butanone cluster ion has been monitored over a range of internal energies (16000-18800 cm⁻¹). First-order rate constants are acquired for the precursor ion dissociation into three product channels. The temporal growth of each fragment ion is selectively monitored in a custom instrument and yields similar valued rate constants at a common ion internal energy. The decomposition reaction is proposed to proceed along two parallel reaction coordinates. Each dissociative pathway is rate-limited by the initial Ni(+) oxidative addition into either the C-CH₃ or C-C₂H₅ σ-bond in the butanone molecule. Ratios of integrated product ion intensities as well as the measured rate constants are used to determine values for each σ-bond activation rate constant. The lowest energy measurement presented in this study occurs when the binary complex ion possesses an internal energy of 16000 cm⁻¹. Under this condition, the Ni(+) assisted decomposition of the butanone molecule is rate limited by k(act)(C-C₂H₅) = (0.92 ± 0.08) × 10⁵ s⁻¹ and k(act)(C-CH₃) = (0.37 ± 0.03) × 10⁵ s⁻¹. The relative magnitudes of the two rate constants reflect the greater probability for reaction to occur along the C-C₂H₅ σ-bond insertion pathway, consistent with thermodynamic arguments. DFT calculations at the B3LYP/6-311++G(d,p) level of theory suggest the most likely geometries and relative energies of the reactants, intermediates, and products.

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COMPUTER MODELS OF THE AGS, I : The D. C. Bare Machine at High Fields

Cited by 5 publications

References 0 publications

Structural Determinants of Human FANCF Protein That Function in the Assembly of a DNA Damage Signaling Complex

Structural Determinants of Human FANCF Protein That Function in the Assembly of a DNA Damage Signaling Complex

Photoinduced Br Desorption from CsBr Thin Films Grown on Cu(100)

Reaction Rate Constants and Mechanistic Detail of the Ni⁺+ Butanone Reaction

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COMPUTER MODELS OF THE AGS, I : The D. C. Bare Machine at High Fields

Cited by 5 publications

References 0 publications

Structural Determinants of Human FANCF Protein That Function in the Assembly of a DNA Damage Signaling Complex

Structural Determinants of Human FANCF Protein That Function in the Assembly of a DNA Damage Signaling Complex

Photoinduced Br Desorption from CsBr Thin Films Grown on Cu(100)

Reaction Rate Constants and Mechanistic Detail of the Ni++ Butanone Reaction

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Reaction Rate Constants and Mechanistic Detail of the Ni⁺+ Butanone Reaction