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Articles 1 - 12 of 12
Full-Text Articles in Entire DC Network
Assembly And Disassembly Of Dna Polymerase Holoenzyme, Daniel J. Sexton, Anthony J. Berdis, Stephen J. Benkovic
Assembly And Disassembly Of Dna Polymerase Holoenzyme, Daniel J. Sexton, Anthony J. Berdis, Stephen J. Benkovic
Chemistry Faculty Publications
The complex task of genomic replication requires a large collection of proteins properly assembled within the close confines of the replication fork. The mechanism and dynamics of holoenzyme assembly and disassembly have been investigated using steady state and pre-steady state methods as opposed to structural studies, primarily due to the intrinsic transient nature of these protein complexes during DNA replication. The key step in bacteriophage T4 holoenzyme assembly involves ATP hydrolysis, whereas disassembly is mediated by subunit dissociation of the clamp protein in an ATP-independent manner.
Electron Transfer Across A Peptide-Peptide Interface Within A Designed Metalloprotein, Gennady V. Kozlov, Michael Y. Ogawa
Electron Transfer Across A Peptide-Peptide Interface Within A Designed Metalloprotein, Gennady V. Kozlov, Michael Y. Ogawa
Chemistry Faculty Publications
Mechanistic studies of biological electron-transfer (ET) reactions have involved the use of surface-derivatized proteins, protein−protein complexes, and polypeptide-bridged donor−acceptor compounds. These latter studies seek to use well-defined model systems to better define the role of the intervening protein matrix in mediating biological electron transfers. However, whereas many in vivo ET reactions occur across a noncovalent protein−protein interface, the primary role of the peptide spacers found in current model systems is to provide a covalent link between the donor and acceptor sites. As such, these systems are poorly suited to probe the mechanisms of ET reactions occurring across a peptide−peptide interface.
Rounding Numbers: Why The ''New System'' Doesn't Work, W. Robert Midden
Rounding Numbers: Why The ''New System'' Doesn't Work, W. Robert Midden
Chemistry Faculty Publications
This paper explains a correction to the rounding rule previously publishedin this Journal. The earlier article reported that the best way to roundnumbers is to always round up when the first digit dropped is 5. However,this will lead to accumulation of error when errors are averaged. Arounding strategy that leads to less error is to round up when 5 isfollowed by any nonzero digits, but to round even when 5 is followed byzeros or no other digits. By rounding the last kept digit to an evennumber, half the time the digit is increased and half the time it is keptthe …
Partitioning Of The Reactive Nitrogen Reservoir In The Lower Sratosphere Of The Southern Hemisphere: Observations And Modeling, R. S. Gao, D. W. Fahey, R. J. Salawitch, S. A. Lloyd, D. E. Anderson, R. Demajistre, C. T. Mcelroy, E. L. Woodbridge, R. C. Wamsley, S. G. Donnelly, L. A. Del Negro, M. H. Proffitt, R. M. Stimpfle, D. W. Kohn, S. R. Kawa, L. R. Lait, M. Loewenstein, J. R. Podolske, E. R. Keim, J. E. Dye, J. C. Wilson, K. R. Chan
Partitioning Of The Reactive Nitrogen Reservoir In The Lower Sratosphere Of The Southern Hemisphere: Observations And Modeling, R. S. Gao, D. W. Fahey, R. J. Salawitch, S. A. Lloyd, D. E. Anderson, R. Demajistre, C. T. Mcelroy, E. L. Woodbridge, R. C. Wamsley, S. G. Donnelly, L. A. Del Negro, M. H. Proffitt, R. M. Stimpfle, D. W. Kohn, S. R. Kawa, L. R. Lait, M. Loewenstein, J. R. Podolske, E. R. Keim, J. E. Dye, J. C. Wilson, K. R. Chan
Chemistry Faculty Publications
Measurements of nitric oxide (NO), nitrogen dioxide (NO2), and total reactive nitrogen (NOy = NO + NO2 + NO3 + HNO3 + ClONO2 + 2N2O5 + ...) were made during austral fall, winter, and spring 1994 as part of the NASA Airborne Southern Hemisphere Ozone Experiment/Measurements for Assessing the Effects of Stratospheric Aircraft mission. Comparisons between measured NO2 values and those calculated using a steady state (SS) approximation are presented for flights at mid and high latitudes. The SS results agree with the measurements to within 8%, suggesting that the kinetic rate coefficients and calculated NO2 photolysis rate used in …
Conformations And Relative Stabilities Of The Cis And Trans Isomers In A Series Of Isolated N-Phenylamides, V. P. Manea, K. J. Wilson, John R. Cable
Conformations And Relative Stabilities Of The Cis And Trans Isomers In A Series Of Isolated N-Phenylamides, V. P. Manea, K. J. Wilson, John R. Cable
Chemistry Faculty Publications
The gas-phase conformations of a series of isolated N-phenylamides have been determined from vibrationally resolved electronic spectra obtained by resonant two-photon ionization in a supersonic jet expansion. Both the cis and trans isomers of formanilide were identified, with the cis isomer in 6.5% abundance. The spectral features displayed by this isomer are consistent with a nonplanar geometry which undergoes a large change in the phenyl torsional angle following electronic excitation. The more abundant trans isomer of formanilide adopts a planar structure and is stabilized by 2.5 kcal/mol with respect to the cis isomer. In the excited electronic state the relative …
Enhancing The Performance Of Membrane Introduction Mass Spectrometry By Organic Carrier And Liquid Chromatographic Separation, Shi Ouyang, Yong Hong Chen, Yan Xu
Enhancing The Performance Of Membrane Introduction Mass Spectrometry By Organic Carrier And Liquid Chromatographic Separation, Shi Ouyang, Yong Hong Chen, Yan Xu
Chemistry Faculty Publications
A method of membrane introduction mass spectrometry with liquid chromatographic separation (LC/MIMS) for the analysis of volatile organic compounds (VOCs) in water has been developed. The method not only inherited all the advantages of membrane introduction mass spectrometry by flow-injection analysis (FIA/MIMS), but also expanded the application of MIMS to the determination of compounds with identical quantitation ions. Because the quantitation by LC/MIMS is based on two-dimensional identification (retention time (tr) and mass-to-charge ratio ()), it provides a tangible approach to the analysis of VOCs in complex aqueous samples. In this work, a C18 column and a mobile phase (methanol/water) …
Identification Of The Adp-L-Glycero-D-Manno-Heptose-6-Epimerase (Rfad) And Heptosyltransferase Ii (Rfaf) Biosynthesis Genes From Nontypeable Haemophilus Influenzae 2019, W A. Nichols, B W. Gibson, William Melaugh, N G. Lee, M Sunshine, M A. Apicella
Identification Of The Adp-L-Glycero-D-Manno-Heptose-6-Epimerase (Rfad) And Heptosyltransferase Ii (Rfaf) Biosynthesis Genes From Nontypeable Haemophilus Influenzae 2019, W A. Nichols, B W. Gibson, William Melaugh, N G. Lee, M Sunshine, M A. Apicella
Chemistry Faculty Publications
Haemophilus influenzae is an important human pathogen. The lipooligosaccharide (LOS) of H. influenzae has been implicated as a virulence determinant. To better understand the assembly of LOS in nontypeable H. influenzae (NtHi), we have cloned and characterized the rfaD and rfaF genes of NtHi 2019, which encode the ADP-L-glycero-D-manno-heptose-6-epimerase and heptosyltransferase II enzymes, respectively. This cloning was accomplished by the complementation of Salmonella typhimurium lipopolysaccharide (LPS) biosynthesis gene mutants. These deep rough mutants are novobiocin susceptible until complemented with the appropriate gene. In this manner, we are able to use novobiocin resistance to select for specific NtHi LOS inner core …
Characterization Of A Transposon Tn916-Generated Mutant Of Haemophilus Ducreyi 35000 Defective In Lipooligosaccharide Biosynthesis, B W. Gibson, A A. Campagnari, William Melaugh, M A. Apicella, S Grass, Jing Wang, Katherine L. Palmer, R S. Munson
Characterization Of A Transposon Tn916-Generated Mutant Of Haemophilus Ducreyi 35000 Defective In Lipooligosaccharide Biosynthesis, B W. Gibson, A A. Campagnari, William Melaugh, M A. Apicella, S Grass, Jing Wang, Katherine L. Palmer, R S. Munson
Chemistry Faculty Publications
To define the role of the surface lipooligosaccharide (LOS) of Haemophilus ducreyi in the pathogenesis of chancroid, Tn916 mutants of H. ducreyi 35000 defective in expression of the murine monoclonal antibody (MAb) 3F11 epitope on H. ducreyi LOS were identified by immunologic screening. One mutant, designated 1381, has an LOS which lacks the MAb 3F11 epitope and migrates with an increased mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The gene disrupted by the Tn916 element in strain 1381 was identified by cloning the sequences flanking the Tn916 element. The sequences were then used to probe a lambda DASHII genomic library. …
The Role Of HoX In Super- And Subsonic Aircraft Exhaust Plumes, T. F. Hanisco, P. O. Wennberg, R. C. Cohen, J. G. Anderson, D. W. Fahey, E. R. Keim, R. S. Gao, R. C. Wamsley, Stephen G. Donnelly Ph.D., L. A. Del Negro, R. J. Salawitch, K. K. Kelly, M. H. Proffitt
The Role Of HoX In Super- And Subsonic Aircraft Exhaust Plumes, T. F. Hanisco, P. O. Wennberg, R. C. Cohen, J. G. Anderson, D. W. Fahey, E. R. Keim, R. S. Gao, R. C. Wamsley, Stephen G. Donnelly Ph.D., L. A. Del Negro, R. J. Salawitch, K. K. Kelly, M. H. Proffitt
Chemistry Faculty Publications
The generation of sulfuric acid aerosols in aircraft exhaust has emerged as a critical issue in determining the impact of supersonic aircraft on stratospheric ozone. It has long been held that the first step in the mechanism of aerosol formation is the oxidation of SO2 emitted from the engine by OH in the exhaust plume. We report in situ measurements of OH and HO2 in the exhaust plumes of a supersonic (Air France Concorde) and a subsonic (NASA ER-2) aircraft in the lower stratosphere. These measurements imply that reactions with OH are responsible for oxidizing only a small fraction of …
Efficient And General Synthesis Of Novel Β-Polyfluoroalkoxy Vinamidinium Salts, Koichiro Kase, Mitsuyoshi Katayama, Takashi Ishihara, Hiroki Yamanaka, John T. Gupton
Efficient And General Synthesis Of Novel Β-Polyfluoroalkoxy Vinamidinium Salts, Koichiro Kase, Mitsuyoshi Katayama, Takashi Ishihara, Hiroki Yamanaka, John T. Gupton
Chemistry Faculty Publications
Novel β-polyfluoroalkoxy vinamidinium salts 3 and/or 4 were synthesized in good yields by the reaction of N-(2- polyfluoroalkoxy-3 ,3-difluoro-1-propenyI)trimethylammonium iodides (2), prepared from N-(2,3,3-trifluoro-1-propenyl)trimethylammonium iodide (1), with secondary amines in MeCN at 70 °C for 1 h. The salts were also obtainable in comparable yields by the one-pot reaction of 1 with sodium polyfluoroalkoxide followed by treatment with amines.
The Effects Of Exercise Training On Resting Prostacyclin And Thromboxane A(2) In Older Adults, R D. Kauffman, G S. Sforzo, Blaise Frost, M K. Todd
The Effects Of Exercise Training On Resting Prostacyclin And Thromboxane A(2) In Older Adults, R D. Kauffman, G S. Sforzo, Blaise Frost, M K. Todd
Chemistry Faculty Publications
Ten adult volunteers participated in 16 weeks of cardiovascular exercise training (EG) to determine the effects of training on resting prostacyclin (PGI(2)) and thromboxane A(2) (TXA(2)). Six volunteers of similar age served as sedentary controls (CG). Blood was collected in tubes after training and eicosanoids were measured by standard I-125 RIA methods. Over the 16 weeks of the study, PGI(2) decreased 48% for EG and 33% for CG. There were no between-group differences for PGI(2) values. No significant within-group changes in TXA(2) were found, whereas between-group pretraining TXA(2) values were significantly different. A time main effect for PGI(2) may indicate …
Properties And Macromolecular Structure Of Unacetylated And Acetylated Nata De Coco, Ma. Assunta C. Cuyegkeng, Ma. Amy L. Dimalanta
Properties And Macromolecular Structure Of Unacetylated And Acetylated Nata De Coco, Ma. Assunta C. Cuyegkeng, Ma. Amy L. Dimalanta
Chemistry Faculty Publications
This study aims to gain more insight into the supramolecular structure of the cellulose in nata de coco, and to compare its ability to be modified with the known types of cellulose. The investigations were done using IR spectroscopy and thennal analysis. The IR spectra of microcrystalline cellulose were identical to cellulose spectra. However, those of dried nata de coco cellulose showed additional peaks that indicated a loss of inter- and intra-sheet hydrogen bonding, usually extensive in other cellulose forms where sheets are the prevalent secondary structures. This kind of structure would be consistent with the necessary framework for gel …