Calculations of enzymic reactions: calculations of pKa, proton transfer reactions, and general acid catalysis reactions in enzymes

Biochemistry ◽  
1981 ◽  
Vol 20 (11) ◽  
pp. 3167-3177 ◽  
Author(s):  
Arieh Warshel
Keyword(s):  
Proton Transfer ◽  
Acid Catalysis ◽  
Transfer Reactions ◽  
General Acid ◽  
Proton Transfer Reactions

scholarly journals Energetics and dynamics of proton transfer reactions along short water wires

2011 ◽  
Vol 13 (29) ◽  
pp. 13207 ◽  
Author(s):  
Ville R. I. Kaila ◽  
Gerhard Hummer
Keyword(s):  
Proton Transfer ◽  
Transfer Reactions ◽  
Proton Transfer Reactions

Integration of Ultraviolet Photodissociation with Proton Transfer Reactions and Ion Parking for Analysis of Intact Proteins

2015 ◽  
Vol 88 (1) ◽  
pp. 1008-1016 ◽  
Author(s):  
Dustin D. Holden ◽  
William M. McGee ◽  
Jennifer S. Brodbelt
Keyword(s):  
Proton Transfer ◽  
Transfer Reactions ◽  
Intact Proteins ◽  
Ultraviolet Photodissociation ◽  
Proton Transfer Reactions

Theoretical studies of proton-transfer reactions. II. Reaction of water wih hydride ion

1968 ◽  
Vol 90 (4) ◽  
pp. 833-838 ◽  
Author(s):  
Calvin D. Ritchie ◽  
Harry Frederick. King
Keyword(s):  
Proton Transfer ◽  
Transfer Reactions ◽  
Theoretical Studies ◽  
Hydride Ion ◽  
Proton Transfer Reactions

A Potentiometric Study on Proton-Transfer Equilibria and Cationic Conjugation in Pyridine N-Oxide Systems in Acetone and Methanol

1996 ◽  
Vol 49 (9) ◽  
pp. 931 ◽  
Author(s):  
L Chmurzynski ◽  
E Kaczmarczyk ◽  
M Nesterowicz ◽  
G Wawrzyniak ◽  
Z Warnke
Keyword(s):  
Proton Transfer ◽  
Equilibrium Constants ◽  
Proton Donor ◽  
Heterocyclic Amines ◽  
Transfer Reactions ◽  
Oxide Systems ◽  
Experimental Systems ◽  
Proton Transfer Reactions ◽  
Potentiometric Titration Method

The potentiometric titration method has been used to study the equilibria of cationic in sytems formed by substituted pyridine N-oxides in the polar, non-aqueous solvents acetone and methanol. For comparison, the systems with trimethylamine N-oxide as a representative of aliphatic amine N-oxides and pyridine representing parent heterocyclic amines were also studied. The cationic heteroconjugation constants, i.e. the equilibrium constants for conjugation reactions between free and protonated N-bases leading to the formation of unsymmetric BHB'+ cations, were determined in experimental systems with and without proton transfer. It was found that there were significant differences in the values of the cationic heteroconjugation constants determined in these two acid-base systems. The proton-transfer reactions limit and even preclude the determination of the cationic heteroconjugation constants. On this basis it was concluded that the heteroconjugation constants should be determined in systems without proton transfer. In such systems, in the amphiprotic solvent methanol, cationic heteroconjugation was ascertained in all substituted pyridine N-oxide systems, the values of heteroconjugation constants being relatively low (logarithms of their values of the order of 2-2.5), and only negligible in systems involving trimethylamine N-oxide. A more pronounced tendency towards cationic heteroconjugation of the [OHO]+ type was observed in the aprotic protophobic acetone, where heteroconjugation constants were determined for all amine N-oxide systems studied including those containing protonated trimethylamine N-oxide as a proton donor. However, the values of the cationic heteroconjugation constants were found to be, in methanol likewise, relatively low (log KBHB'+ of the order of 2-3). On the contrary, a greater extent of cationic heteroconjugation equilibria was observed in methanol than in acetone in the case of systems containing pyridine, i.e. [NHO]+ type bridges formed by amine N-oxides and heterocyclic amines. In methanol the heteroconjugation constants turned out to be determinable for all such systems studied (logarithms of the equilibrium constants being of the same order as for N-oxide systems), whereas in acetone the hetero constants were indeterminable for all systems.

Gas-phase proton-transfer reactions of the hydronium ion at 298 K

1979 ◽  
Vol 57 (12) ◽  
pp. 1518-1523 ◽  
Author(s):  
Gervase I. Mackay ◽  
Scott D. Tanner ◽  
Alan C. Hopkinson ◽  
Diethard K. Bohme
Keyword(s):  
Proton Transfer ◽  
Gas Phase ◽  
Rate Constants ◽  
Transfer Reactions ◽  
Flowing Afterglow ◽  
Hydronium Ion ◽  
Proton Transfer Reactions

Rate constants measured with the flowing afterglow technique at 298 ± 2 K are reported for the proton-transfer reactions of H3O+ with CH2O, CH3CHO, (CH3)2CO, HCOOH, CH3COOH, HCOOCH3, CH3OH, C2H5OH, (CH3)2O, and CH2CO. Dissociative proton-transfer was observed only with CH3COOH. The rate constants are compared with the predictions of various theories for ion–molecule collisions. The protonation is discussed in terms of the energetics and mechanisms of various modes of dissociation.

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