scholarly journals Mechanism of Flavoprotein l-6-Hydroxynicotine Oxidase: pH and Solvent Isotope Effects and Identification of Key Active Site Residues

Biochemistry ◽  
2017 ◽  
Vol 56 (6) ◽  
pp. 869-875 ◽  
Author(s):  
Paul F. Fitzpatrick ◽  
Fatemeh Chadegani ◽  
Shengnan Zhang ◽  
Vi Dougherty
Keyword(s):  
Active Site ◽  
Isotope Effects ◽  
Active Site Residues ◽  
Solvent Isotope ◽  
Solvent Isotope Effects

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

scholarly journals Rate and Product Studies with 1-Adamantyl Chlorothioformate under Solvolytic Conditions

2021 ◽  
Vol 22 (14) ◽  
pp. 7394
Author(s):  
Kyoung Ho Park ◽  
Mi Hye Seong ◽  
Jin Burm Kyong ◽  
Dennis N. Kevill
Keyword(s):  
Rate Constants ◽  
Isotope Effects ◽  
Ion Pairs ◽  
Carbonyl Sulfide ◽  
Activation Parameters ◽  
Chloride Ions ◽  
Reaction Channels ◽  
Decomposition Pathway ◽  
Solvent Isotope ◽  
Solvent Isotope Effects

A study was carried out on the solvolysis of 1-adamantyl chlorothioformate (1-AdSCOCl, 1) in hydroxylic solvents. The rate constants of the solvolysis of 1 were well correlated using the Grunwald–Winstein equation in all of the 20 solvents (R = 0.985). The solvolyses of 1 were analyzed as the following two competing reactions: the solvolysis ionization pathway through the intermediate (1-AdSCO)+ (carboxylium ion) stabilized by the loss of chloride ions due to nucleophilic solvation and the solvolysis–decomposition pathway through the intermediate 1-Ad+Cl− ion pairs (carbocation) with the loss of carbonyl sulfide. In addition, the rate constants (kexp) for the solvolysis of 1 were separated into k1-Ad+Cl− and k1-AdSCO+Cl− through a product study and applied to the Grunwald–Winstein equation to obtain the sensitivity (m-value) to change in solvent ionizing power. For binary hydroxylic solvents, the selectivities (S) for the formation of solvolysis products were very similar to those of the 1-adamantyl derivatives discussed previously. The kinetic solvent isotope effects (KSIEs), salt effects and activation parameters for the solvolyses of 1 were also determined. These observations are compared with those previously reported for the solvolyses of 1-adamantyl chloroformate (1-AdOCOCl, 2). The reasons for change in reaction channels are discussed in terms of the gas-phase stabilities of acylium ions calculated using Gaussian 03.

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