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Full-Text Articles in Physical Sciences and Mathematics
Protein-Protein And Protein-Dna Interactions At The Bacteriophage T4 Dna Replication Fork. Characterization Of A Fluorescently Labeled Dna Polymerase Sliding Clamp, Daniel J. Sexton, Theodore E. Carver, Anthony J. Berdis, Stephen J. Benkovic
Protein-Protein And Protein-Dna Interactions At The Bacteriophage T4 Dna Replication Fork. Characterization Of A Fluorescently Labeled Dna Polymerase Sliding Clamp, Daniel J. Sexton, Theodore E. Carver, Anthony J. Berdis, Stephen J. Benkovic
Chemistry Faculty Publications
The T4 DNA polymerase holoenzyme is composed of the polymerase enzyme complexed to the sliding clamp (the 45 protein), which is loaded onto DNA by an ATP-dependent clamp loader (the 44/62 complex). This paper describes a new method to directly investigate the mechanism of holoenzyme assembly using a fluorescently labeled cysteine mutant of the 45 protein. This protein possessed unaltered function yet produced substantial changes in probe fluorescence intensity upon interacting with other components of the holoenzyme. These fluorescence changes provide insight into the role of ATP hydrolysis in holoenzyme assembly. Using either ATP or the non-hydrolyzable ATP analog, adenosine …
The Carboxyl Terminus Of The Bacteriophage T4 Dna Polymerase Is Required For Holoenzyme Complex Formation, Anthony J. Berdis, Patrice Soumillion, Stephen J. Benkovic
The Carboxyl Terminus Of The Bacteriophage T4 Dna Polymerase Is Required For Holoenzyme Complex Formation, Anthony J. Berdis, Patrice Soumillion, Stephen J. Benkovic
Chemistry Faculty Publications
To further elucidate the mechanism and dynamics of bacteriophage T4 holoenzyme formation, a mutant polymerase in which the last six carboxyl-terminal amino acids are deleted, was constructed, overexpressed, and purified to homogeneity. The mutant polymerase, designated ΔC6 exo−, is identical to wild-type exo− polymerase with respect to kcat, kpol, and dissociation constants for nucleotide and DNA substrate. However, unlike wild-type exo− polymerase, the ΔC6 exo− polymerase is unable to interact with the 45 protein to form the stable holoenzyme. A synthetic polypeptide corresponding to the carboxyl terminus of the wild-type exo− polymerase was tested as an in vitro inhibitor of …
Electronic Spectroscopy Of Jet-Cooled Benzylidenecyclobutane, A Sterically Hindered Styrene, John R. Cable, V. P. Manea
Electronic Spectroscopy Of Jet-Cooled Benzylidenecyclobutane, A Sterically Hindered Styrene, John R. Cable, V. P. Manea
Chemistry Faculty Publications
The electronic spectrum of the styrene derivative, benzylidenecyclobutane, seeded in a supersonic jet expansion has been recorded using resonantly enhanced two-photon ionization spectroscopy. The main vibronic features in the spectrum are associated with a low frequency progression assigned to the torsional motion of the phenyl ring. Analysis of the observed torsional levels reveals an excited state potential energy surface characteristic of a planar equilibrium geometry which undergoes large amplitude motion and a ground state surface having a minimum at a torsional angle of 25° between the phenyl and vinyl groups. Ab initio calculations of the ground state torsional potential surface …
The Role Of Written And Verbal Expression In Improving Communication Skills For Students In An Undergraduate Chemistry Program, Brian P. Coppola, Douglas S. Daniels
The Role Of Written And Verbal Expression In Improving Communication Skills For Students In An Undergraduate Chemistry Program, Brian P. Coppola, Douglas S. Daniels
Chemistry Faculty Publications
Proofreading, editing, and critique, the customary assessment tools scientists use to evaluate professional journal articles, grant applications, and any other writing, can be applied equally well in introductory science instruction. Such feedback is, in fact, crucial to growth and development. When learning anything new, students and faculty alike rely heavily on sources other than themselves (‘external editors’) to assess their understanding as they develop self-assessment skills (or ‘internal editors’). Although they rarely describe it in these terms, faculty nonetheless assume that students have developed and refined their internal skills by the time they take examinations and write term papers. Unfortunately, …
Indirect Ultraviolet Detection Of Biologically Relevant Organic Acids By Capillary Electrophoresis, Hong Chen, Yan Xu, Frederick Van Lente, Michael P.C. Ip
Indirect Ultraviolet Detection Of Biologically Relevant Organic Acids By Capillary Electrophoresis, Hong Chen, Yan Xu, Frederick Van Lente, Michael P.C. Ip
Chemistry Faculty Publications
Indirect UV detection of fourteen short-chain organic acids (e.g., oxalic acid, citric acid, malonic acid, tartaric acid, methylmalonic acid, α-ketoglutaric acid, succinic acid, ethylmalonic acid, methylsuccinic acid, glutaric acid, apidic acid, methylglutaric acid, lactic acid and pyruvic acid) by capillary electrophoresis is described. The method used phthalate as the UV-absorbing additive in carbonate buffer and the non-absorbing analytes were detected indirectly at 230 nm. The influences of buffer pH, ionic strenght, concentration of phthalate and organic modifier on indirect signal response and migration behavior of the organic acids were investigated. Comparisons of reproducibility on migration time, limit of detection and …
Computation Of Electron Affinities Of O And F Atoms, And Energy Profile Of F-H2 Reaction By Density Functional Theory And Ab Initio Methods, Branko S. Jursic
Computation Of Electron Affinities Of O And F Atoms, And Energy Profile Of F-H2 Reaction By Density Functional Theory And Ab Initio Methods, Branko S. Jursic
Chemistry Faculty Publications
The validity of hybrid and nonlocal DFT methods are tested on examples of systems which are difficult to model by way of quantum chemistry techniques. The electron affinities for the oxygen and fluorine atoms were calculated. The exothermicity, the barrier for the fluorine atom reaction with the hydrogen molecule, and the energy of the H–F bond and its distance were computed with DFT methods, as well as, with ROHF, MPn, and QCISD ~T! ab initio methods. The computations were performed by using various basis sets, with 6-311 11G(3d f ,3pd as the largest. The obtained results are compared …
Photoinduced Electron Transfer Along A Beta-Sheet Mimic, Alexei B. Gretchikhine, Michael Y. Ogawa
Photoinduced Electron Transfer Along A Beta-Sheet Mimic, Alexei B. Gretchikhine, Michael Y. Ogawa
Chemistry Faculty Publications
Electron energy-loss spectroscopy (EELS) is used to determine the energies of low-lying singlet and triplet states of the title compound. The EELS measurements give a splitting of 0.45 eV between the two lowest π f π* singlet states, as confirmed by optical absorption measurements, but do not give a discernable splitting between the corresponding triplet states. The experimental results are interpreted with the aid of ab initio electronic structure calculations using the CIS and CASPT2 methods. The calculations are consistent with the experiments, giving a much larger splitting between the π f π* singlet as compared to the π f …
The Lipooligosaccharides Of Haemophilus Ducreyi Are Highly Sialylated, William Melaugh, A A. Campagnari, B W. Gibson
The Lipooligosaccharides Of Haemophilus Ducreyi Are Highly Sialylated, William Melaugh, A A. Campagnari, B W. Gibson
Chemistry Faculty Publications
The major lipooligosaccharides of the sexually transmitted pathogen Haemophilus ducreyi 35000 have been previously found to terminate in N-acetyllactosamine and sialyl-N-acetyllactosamine, Neu5Ac alpha 2-->3Gal beta 1-->4GlcNAc (W. Melaugh, N. J. Phillips, A. A. Campagnari, M. V. Tullius, and B. W. Gibson, Biochemistry 33: 13070-13078, 1994). In this study, mass spectrometry and composition analyses have shown that the lipooligosaccharides from three other H. ducreyi strains also contain N-acetyllactosamine and are highly sialylated (approximately 30 to 50%), although one African strain was found to contain neither of these structural features.