Phosphorylation of the calcium-transporting adenosinetriphosphatase by lanthanum ATP: rapid phosphoryl transfer following a rate-limiting conformational change

Biochemistry ◽  
1990 ◽  
Vol 29 (21) ◽  
pp. 5210-5220 ◽  
Author(s):  
Arthur M. Hanel ◽  
William P. Jencks
Keyword(s):  
Conformational Change ◽  
Phosphoryl Transfer ◽  
Rate Limiting

scholarly journals The Relationship between Enzyme Conformational Change, Proton Transfer, and Phosphoryl Transfer in β-Phosphoglucomutase

ACS Catalysis ◽  
2021 ◽  
pp. 12840-12849
Author(s):  
Angus J. Robertson ◽  
Alex L. Wilson ◽  
Matthew J. Burn ◽  
Matthew J. Cliff ◽  
Paul L. A. Popelier ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Conformational Change ◽  
Phosphoryl Transfer ◽  
The Relationship

scholarly journals Kinetics and Thermodynamics of the Rate-Limiting Conformational Change in the Actomyosin V Mechanochemical Cycle

2011 ◽  
Vol 407 (5) ◽  
pp. 716-730 ◽  
Author(s):  
Donald J. Jacobs ◽  
Darshan Trivedi ◽  
Charles David ◽  
Christopher M. Yengo
Keyword(s):  
Conformational Change ◽  
Kinetics And Thermodynamics ◽  
Mechanochemical Cycle ◽  
Rate Limiting

scholarly journals Catalysis by acetylcholinesterase in two-hydronic-reactive states. Integrity of deuterium oxide effects and hydron inventories

1992 ◽  
Vol 285 (2) ◽  
pp. 451-460 ◽  
Author(s):  
E Salih
Keyword(s):  
Kinetic Parameters ◽  
Conformational Change ◽  
Rate Constants ◽  
Literature Abstract ◽  
Deuterium Oxide ◽  
Ph Dependence ◽  
Reversible Inhibitor ◽  
Induced Fit ◽  
Rate Limiting ◽  
Hydrolysis Of

Low 2H2O effects (1.0-1.5) for the parameter k(cat.)/Km in the hydrolysis of various substrates by acetylcholinesterase (AcChE) is due to normal 2H2O effects (1.8-2.8) for the parameter k(cat.) and 2H2O effects of 1.0-2.5 for the parameter Km. The analyses and interpretations of 2H2O effects in the literature utilizing the parameter k(cat.)/Km, which led to the proposal of ‘isotope insensitivity’ of the catalytic steps and the hypothesis of a rate-limiting substrate-induced-fit conformational change, are incorrect. Since k(cat.) is the only parameter that can represent the hydron-transfer step solely, the 2H2O effect can most appropriately be evaluated by using this parameter. Calculations and comparison of acylation (k+2) and deacylation (k+3) rate constants show that acylation is rate-determining for most substrates and the improved binding -0.84 to -2.09 kJ/mol (-0.2 to -0.5 kcal/mol) in 2H2O obscures the normal 2H2O effect on k(cat.) when the ratio k(cat.)/Km is utilized. Consistent with this, measurements of the inhibition constant (KI(com.)) for a reversible inhibitor, phenyltrimethylammonium, lead to KI(com.)H2O = 39 +/- 3 microM and KI(com.)2H2O = 24.5 +/- 3.5 microM, an 2H2O effect of 1.59 +/- 0.26. pH-dependence of k(cat.) in 2H2O is subject to variability of the pK(app.) values, as evaluated in terms of the two-hydronic-reactive states (EH and EH2) of AcChE, and is due to an uneven decrease in 2H2O of the kinetic parameters k'cat. for the EH2 state relative to k(cat.) for the EH state, thus leading to variable shifts in pK(app.) values of between 0.5 and 1.2 pH units for this parameter. The observed pH-independent limiting rate constants for k(cat.)/Km(app.) are made to vary between 0.5 and 1.0 in 2H2O by effects on kinetic parameters for the EH2 state, k'cat./K'm varying between 0.2 and 0.7 relative to the EH state, with k(cat.)/Km varying between 0.4 and 1.0. The effects observed on k(cat.)/Km(app.) are ultimately the result of variable effects of 2H2O on k'cat. and K'm for the EH2 state relative to k(cat.) and Km for the EH state of AcChE. These effects are responsible for the variable shifts and more than 0.5 pH unit of the pK(app.) values in 2H2O for pH-k(cat.)/Km profiles. The upward-bowing hydron inventories for k(cat.)/Km are the result of linear hydron inventories for k(cat.) and downward-bowing on Km and are not due to the rate-limiting substrate-induced fit process as claimed in the literature.(ABSTRACT TRUNCATED AT 400 WORDS)

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