Vibrational analysis of the chorismate rearrangement: relaxed force constants, isotope effects and activation entropies calculated for reaction in vacuum, water and the active site of chorismate mutase

2004 ◽  
Vol 17 (67) ◽  
pp. 592-601 ◽  
Author(s):  
Giuseppe D. Ruggiero ◽  
Sara J. Guy ◽  
Sergio Martí ◽  
Vicent Moliner ◽  
Ian H. Williams
Keyword(s):  
Active Site ◽  
Isotope Effects ◽  
Vibrational Analysis ◽  
Force Constants ◽  
Chorismate Mutase

QM/MM calculations of kinetic isotope effects in the chorismate mutase active site

2003 ◽  
Vol 1 (3) ◽  
pp. 483-487 ◽  
Author(s):  
Sergio Martí ◽  
Vicent Moliner ◽  
Iñaki Tuñón ◽  
Ian H. Williams
Keyword(s):  
Active Site ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Chorismate Mutase ◽  
Kinetic Isotope

Kinetic isotope effects in the active site ofB. subtilis chorismate mutase

2003 ◽  
Vol 94 (5) ◽  
pp. 287-292 ◽  
Author(s):  
Sharon E. Worthington ◽  
Adrian E. Roitberg ◽  
Morris Krauss
Keyword(s):  
Active Site ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Chorismate Mutase ◽  
Kinetic Isotope

Berechnung kinetischer Isotopeneffekte für die Reaktion von Methyljodid mit Cyanid-Ion

1966 ◽  
Vol 21 (9) ◽  
pp. 1377-1384
Author(s):  
A. V. Willi
Keyword(s):  
Transition State ◽  
Secular Equation ◽  
Isotope Effects ◽  
Force Constants ◽  
Bond Breaking ◽  
Bending Force ◽  
A Value ◽  
Order Of Magnitude ◽  
Deuterium Isotope Effects ◽  
The Difference

Kinetic carbon-13 and deuterium isotope effects are calculated for the SN2 reaction of CH3I with CN-. The normal vibrational frequencies of CH3I, the transition state I · · · CH3 · · · CN, and the corresponding isotope substituted reactants and transition states are evaluated from the force constants by solving the secular equation on an IBM 7094 computer.Values for 7 force constants of the planar CH3 moiety in the transition state (with an sp2 C atom) are obtained by comparison with suitable stable molecules. The stretching force constants related to the bonds being broken or newly formed (fCC, fCC and the interaction between these two stretches, /12) are chosen in such a way that either a zero or imaginary value for νʟ≠ will result. Agreement between calculated and experimental methyl-C13 isotope effects (k12/ k13) can be obtained only in sample calculations with sufficiently large values of f12 which lead to imaginary νʟ≠ values. Furthermore, the difference between fCI and fCC must be small (in the order of 1 mdyn/Å). The bending force constants, fHCI and fHCC, exert relatively little influence on k12/k13. They are important for the D isotope effect, however. As soon as experimental data on kH/kD are available it will be possible to derive a value for fHCC in the transition state if fHCI is kept constant at 0.205 mdynA, and if fCI, fCC and f12 are held in a reasonable order of magnitude. There is no agreement between experimental and calculated cyanide-C13 isotope effects. Possible explanations are discussed. — Since fCI and fCC cannot differ much it must be concluded that the transition state is relatively “symmetric”, with approximately equal amounts of bond making and bond breaking.

Infrared spectrum, potential constants, and structure of thio-thionyl fluoride

1965 ◽  
Vol 18 (5) ◽  
pp. 627 ◽  
Author(s):  
RD Brown ◽  
GP Pez ◽  
MF O'Dwyer
Keyword(s):  
Electronic Structure ◽  
Infrared Spectrum ◽  
Thermodynamic Functions ◽  
Vibrational Analysis ◽  
Force Constants ◽  
Normal Coordinate ◽  
Infrared Data

An investigation of the infrared spectrum of gaseous thio-thionyl fluoride (SSF2) results in the following assignment of fundamentals: A': v1 760.5�0.2cm-1, v2 718.5�0.2 cm-1, v3 411.2�0.4cm-1, v4 364.1�0.3 cm-1. A": v5 692.3�0.8cm-1, v6 337.6�0.4 cm-1. A normal coordinate vibrational analysis has been performed and a set of ten force constants evaluated. Some conclusions are given regarding the electronic structure of SSF2. Thermodynamic functions based on the usual assumptions have been calculated for SSF2. A set of potential constants has been evaluated for disulphur monoxide, SSO, using the available infrared data.

scholarly journals Mechanism of the Flavoprotein d-6-Hydroxynicotine Oxidase: Substrate Specificity, pH and Solvent Isotope Effects, and Roles of Key Active-Site Residues

Biochemistry ◽  
2019 ◽  
Vol 58 (21) ◽  
pp. 2534-2541
Author(s):  
Paul F. Fitzpatrick ◽  
Vi Dougherty ◽  
Bishnu Subedi ◽  
Jesus Quilantan ◽  
Cynthia S. Hinck ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Active Site ◽  
Isotope Effects ◽  
Active Site Residues ◽  
Solvent Isotope ◽  
Solvent Isotope Effects
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