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Full-Text Articles in Physical Sciences and Mathematics

A Novel Dual Allosteric Activation Mechanism Of Escherichia Coli Adp-Glucose Pyrophosphorylase: The Role Of Pyruvate, Matías D. Asención Diez, Mabel C. Aleanzi, Alberto A. Iglesias, Miguel Ballicora Aug 2014

A Novel Dual Allosteric Activation Mechanism Of Escherichia Coli Adp-Glucose Pyrophosphorylase: The Role Of Pyruvate, Matías D. Asención Diez, Mabel C. Aleanzi, Alberto A. Iglesias, Miguel Ballicora

Chemistry: Faculty Publications and Other Works

Fructose-1,6-bisphosphate activates ADP-glucose pyrophosphorylase and the synthesis of glycogen in Escherichia coli. Here, we show that although pyruvate is a weak activator by itself, it synergically enhances the fructose-1,6-bisphosphate activation. They increase the enzyme affinity for each other, and the combination increases Vmax, substrate apparent affinity, and decreases AMP inhibition. Our results indicate that there are two distinct interacting allosteric sites for activation. Hence, pyruvate modulates E. coli glycogen metabolism by orchestrating a functional network of allosteric regulators. We postulate that this novel dual activator mechanism increases the evolvability of ADP-glucose pyrophosphorylase and its related metabolic control.


On The Origin Of Mode- And Bond-Selectivity In Vibrationally Mediated Reactions On Surfaces, Daniel Killelea, Arthur L. Utz Oct 2013

On The Origin Of Mode- And Bond-Selectivity In Vibrationally Mediated Reactions On Surfaces, Daniel Killelea, Arthur L. Utz

Chemistry: Faculty Publications and Other Works

The experimental observations of vibrational mode- and bond-selective chemistry at the gas–surface interface indicate that energy redistribution within the reaction complex is not statistical on the timescale of reaction. Such behavior is a key prerequisite for efforts to use selective vibrational excitation to control chemistry at the technologically important gas–surface interface. This paper outlines a framework for understanding the origin of non-statistical reactivity on surfaces. The model focuses on the kinetic competition between intramolecular vibrational energy redistribution (IVR) within the reaction complex, which in the long-time limit leads to statistical behavior, and quenching, scattering, or desorption processes that restrict the …


Universal Scaling Of Nonequilibrium Transport In The Kondo Regime Of Single Molecule Devices, G D. Scott, Z K. Keane, Jacob W. Ciszek, J M. Tour, D Natelson Apr 2009

Universal Scaling Of Nonequilibrium Transport In The Kondo Regime Of Single Molecule Devices, G D. Scott, Z K. Keane, Jacob W. Ciszek, J M. Tour, D Natelson

Chemistry: Faculty Publications and Other Works

Scaling laws and universality are often associated with systems exhibiting emergent phenomena possessing a characteristic energy scale. We report nonequilibrium transport measurements on two different types of single molecule transistor devices in the Kondo regime. The conductance at low bias and temperature adheres to a scaling function characterized by two parameters. This result, analogous to that reported recently in semiconductor dots with Kondo temperatures two orders of magnitude lower, demonstrates the universality of this scaling form. We compare the extracted values of the scaling coefficients to previous experimental and theoretical results.


Kondo Resonances And Anomalous Gate Dependence In The Electrical Conductivity Of Single-Molecule Transistors, L H. Yu, Z K. Keane, Jacob W. Ciszek, L Cheng, J M. Tour, T Baruah, M R. Pederson, D Natelson Dec 2005

Kondo Resonances And Anomalous Gate Dependence In The Electrical Conductivity Of Single-Molecule Transistors, L H. Yu, Z K. Keane, Jacob W. Ciszek, L Cheng, J M. Tour, T Baruah, M R. Pederson, D Natelson

Chemistry: Faculty Publications and Other Works

We report Kondo resonances in the conduction of single-molecule transistors based on transition metal coordination complexes. We find Kondo temperatures in excess of 50 K, comparable to those in purely metallic systems. The observed gate dependence of the Kondo temperature is inconsistent with observations in semiconductor quantum dots and a simple single-dot-level model. We discuss possible explanations of this effect, in light of electronic structure calculations.


Electrochemical Studies Of Swelling And Shrinking Of Clay Films, Jia Du Jan 1993

Electrochemical Studies Of Swelling And Shrinking Of Clay Films, Jia Du

Master's Theses

No abstract provided.


A Clay Modified Electrode For Ion-Exchange Voltammetry, Thaddeus S. Wielgos Jan 1993

A Clay Modified Electrode For Ion-Exchange Voltammetry, Thaddeus S. Wielgos

Master's Theses

No abstract provided.


Reactions Of 1-Triptycyl Carbinol And Bis-(1-Triptycyl)-Carbinol, Bryce Arthur Milleville Jan 1993

Reactions Of 1-Triptycyl Carbinol And Bis-(1-Triptycyl)-Carbinol, Bryce Arthur Milleville

Master's Theses

No abstract provided.


Nmr Study Of Na+-H+ And Na+-Li+ Exchange In Human Erythrocytes, Suilan Mo Jan 1993

Nmr Study Of Na+-H+ And Na+-Li+ Exchange In Human Erythrocytes, Suilan Mo

Master's Theses

No abstract provided.


Low Temperature Spectroscopic And Annealing Studies Of Disordered Organic Solids, Dwayne L. Labrake Jan 1992

Low Temperature Spectroscopic And Annealing Studies Of Disordered Organic Solids, Dwayne L. Labrake

Dissertations

No abstract provided.


Spin Label Studies Of Radical Reduction In Normal And Sickle Erythrocyte Membranes Associated With Antioxidants, Yin Zhang Jan 1992

Spin Label Studies Of Radical Reduction In Normal And Sickle Erythrocyte Membranes Associated With Antioxidants, Yin Zhang

Dissertations

No abstract provided.


Remote Dianions In The Synthesis Of Indolizidine Alkaloids, Diana L. C. Green Green Jan 1992

Remote Dianions In The Synthesis Of Indolizidine Alkaloids, Diana L. C. Green Green

Dissertations

No abstract provided.


Copper And Barium As Dietary Discriminants: The Effects Of Diagenesis, J B. Lambert, S V. Simpson, Carole B. Szpunar, J E. Buikstra Jan 1984

Copper And Barium As Dietary Discriminants: The Effects Of Diagenesis, J B. Lambert, S V. Simpson, Carole B. Szpunar, J E. Buikstra

Chemistry: Faculty Publications and Other Works

In skeletons excavated from Woodland sites, copper and barium levels are found to have been contaminated by influx from the soil environment. Electron microprobe scans for both elements show build-up along the outer surface of femur cross sections. Elemental levels for Cu and Ba are lower in the femur or fibula than in the more porous rib. The distribution of Cu in the immediately surrounding soil is highly anisotropic. These observations indicate that Cu and Ba should not be used for dietary inferences about ancient populations without independent evidence that diagenesis is not important.