Kinetic Study on Achiral-to-Chiral Transformation of Achiral Poly(diphenylacetylene)s via Thermal Annealing in Chiral Solvent: Molecular Design Guideline for Conformational Change toward Optically Dissymmetric Structures

2017 ◽  
Vol 51 (1) ◽  
pp. 34-41 ◽  
Author(s):  
Kyo-Un Seo ◽  
Young-Jae Jin ◽  
Hyojin Kim ◽  
Toshikazu Sakaguchi ◽  
Giseop Kwak
Keyword(s):  
Kinetic Study ◽  
Conformational Change ◽  
Thermal Annealing ◽  
Molecular Design ◽  
Design Guideline ◽  
Chiral Transformation

Kinetic Study on Conformational Change in a Single Molecular Species,  3, of  -Conglycinin in an Acidic Ethanol Solution

2004 ◽  
Vol 23 (6) ◽  
pp. 361-369
Author(s):  
Kazunobu Tsumura ◽  
Wataru Kugimiya ◽  
Masahiro Kuwada ◽  
Yuki Shimura ◽  
Hideyo Hasumi
Keyword(s):  
Kinetic Study ◽  
Conformational Change ◽  
Molecular Species ◽  
Ethanol Solution

scholarly journals Activation of dihydrofolate reductase following thiol modification involves a conformational change at the active site

1998 ◽  
Vol 335 (3) ◽  
pp. 643-646 ◽  
Author(s):  
Ying-Xin FAN ◽  
Zhen-Yu LI ◽  
Li ZHU ◽  
Jun-Mei ZHOU
Keyword(s):  
Kinetic Study ◽  
Conformational Change ◽  
Dihydrofolate Reductase ◽  
Conformational Changes ◽  
Active Site ◽  
Chinese Hamster ◽  
Intrinsic Fluorescence ◽  
Activation Mechanism ◽  
Slow Phase ◽  
Ideal System

Compared with the activation of dihydrofolate reductase (DHFR) by protein denaturants and inorganic salts, activation of the enzyme by thiol modification is relatively slow. Thus it is an ideal system for kinetic study of the activation mechanism. We describe here a kinetic study of the activation of DHFRs from chicken liver and Chinese hamster ovary by p-hydroxymercuribenzoate (p-HMB). The conformational changes in the enzyme molecule that result from the modification were monitored by measuring fluorescence enhancement due to the binding of 2-p-toluidinylnaphthalene-6-sulphonate (TNS), and by monitoring changes in the intrinsic fluorescence of the enzyme. Both activation and the conformational change probed by TNS followed pseudo-first-order kinetics, and the rate constants obtained are in good agreement with each other. The change in intrinsic fluorescence is a biphasic process. The rate of the fast phase, which may reflect a change in the microenvironment of Trp-24 at the active site, coincides with the rate of activation and the conformational change probed by TNS. The rate of the slow phase, which reflects a global conformational change, is about one order of magnitude lower than that of activation. The results indicate that the activation of DHFR by p-HMB is due to modification-induced conformational changes at its active site, rather than the modification of the thiol group itself, which is almost complete within the dead-time of the experiment. This study provides kinetic evidence for the proposal that flexibility at the active site is essential for full expression of catalytic activity.

scholarly journals THERMAL DISAPPEARANCE KINETICS OF RADICALS FORMED DURING RADIOLYSIS IN POLYCRYSTALLINE SOLID STATE OF SODIDM WOLFRAMATE DIHYDRATE

2010 ◽  
Vol 18 (18) ◽  
pp. 49-64
Author(s):  
Mihail Contineanu ◽  
Adina-Elena Stanciu ◽  
Iulia Contineanu ◽  
Ana Neacsu
Keyword(s):  
Solid State ◽  
Gamma Irradiation ◽  
Kinetic Study ◽  
Thermal Annealing ◽  
Kinetic Data ◽  
Room Temperature ◽  
Paramagnetic Centers ◽  
Polycrystalline Solid ◽  
Kinetics Of ◽  
Disappearance Kinetics

A kinetic study of the WO4- radical, formed by gamma irradiation of polycrystalline Na2 WO4.2H2O UCB at room temperature has been performed using the EPR technique. A suitable mechanism for the formation of paramagnetic centers by irradiation and thermal annealing is proposed. The mechanism agrees well with the experimental kinetic data.

The kinetics of inactivation of adenylosuccinate lyase: evidence for a substrate-induced conformational change

1969 ◽  
Vol 47 (6) ◽  
pp. 665-672 ◽  
Author(s):  
W. A. Bridger ◽  
L. H. Cohen
Keyword(s):  
Kinetic Study ◽  
Conformational Change ◽  
Initial Rate ◽  
Alkylating Agents ◽  
Free Enzyme ◽  
The Other ◽  
Adenylosuccinate Lyase ◽  
Product Release ◽  
Rate Kinetics ◽  
Kinetics Of

The kinetics of inactivation of adenylosuccinate lyase by the alkylating agents N-ethyl maleimide and iodoacetamide and by photooxidation have been investigated. The inactivation by the alkylating agents indicates that there are several groups on the enzyme whose reaction affects activity. The presence of AMP, a product of the enzymic reaction, decreases the rate of inactivation by both N-ethyl maleimide and iodoacetamide, while the other product, fumarate, has no effect on the rate. In the case of photoinactivation, the rate is accelerated by the presence of AMP. Fumarate, which again has no effect by itself, causes an overall protection of the enzyme from photoinactivation when added in the presence of AMP. The results, suggesting that fumarate is unable to combine with the free enzyme but does combine with the enzyme–AMP complex, are consistent with the strongly preferred sequence of product release determined by a previous initial-rate kinetic study. Both the kinetics of inactivation and the initial-rate kinetics may be interpreted in terms of a mechanism involving the operation of an enzymic conformational change which is allowed only when either AMP or adenylosuccinate is bound to the enzyme.

Annealing Of Radiation Damage in Tungsten

1970 ◽  
Vol 28 ◽  
pp. 412-413
Author(s):  
Robert C. Rau ◽  
John Moteff
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Radiation Damage ◽  
Thermal Annealing ◽  
Neutron Fluence ◽  
Dislocation Loops ◽  
Defect Clusters ◽  
Polycrystalline Tungsten ◽  
Transmission Electron ◽  
Radiation Induced

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.

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