scholarly journals A Remote Mutation Affects the Hydride Transfer by Disrupting Concerted Protein Motions in Thymidylate Synthase

2012 ◽  
Vol 134 (42) ◽  
pp. 17722-17730 ◽  
Author(s):  
Zhen Wang ◽  
Thelma Abeysinghe ◽  
Janet S. Finer-Moore ◽  
Robert M. Stroud ◽  
Amnon Kohen
Keyword(s):  
Thymidylate Synthase ◽  
Hydride Transfer ◽  
Protein Motions

scholarly journals The influence of active site conformations on the hydride transfer step of the thymidylate synthase reaction mechanism

2015 ◽  
Vol 17 (46) ◽  
pp. 30793-30804 ◽  
Author(s):  
Katarzyna Świderek ◽  
Amnon Kohen ◽  
Vicent Moliner
Keyword(s):  
Reaction Mechanism ◽  
Thymidylate Synthase ◽  
Active Site ◽  
Hydride Transfer ◽  
Md Simulations ◽  
Concerted Mechanism ◽  
X Ray ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting

QM/MM MD simulations from different X-ray structures support the concerted mechanism character in the rate limiting step of thymidylate synthase catalysis.

scholarly journals Mg2+ Binds to the Surface of Thymidylate Synthase and Affects Hydride Transfer at the Interior Active Site

2013 ◽  
Vol 135 (20) ◽  
pp. 7583-7592 ◽  
Author(s):  
Zhen Wang ◽  
Paul J. Sapienza ◽  
Thelma Abeysinghe ◽  
Calvin Luzum ◽  
Andrew L. Lee ◽  
...  
Keyword(s):  
Thymidylate Synthase ◽  
Active Site ◽  
Hydride Transfer

Tryptophan 80 and Leucine 143 Are Critical for the Hydride Transfer Step of Thymidylate Synthase by Controlling Active Site Access†,‡

Biochemistry ◽  
2002 ◽  
Vol 41 (22) ◽  
pp. 7021-7029 ◽  
Author(s):  
Timothy A. Fritz ◽  
Lu Liu ◽  
Janet S. Finer-Moore ◽  
Robert M. Stroud
Keyword(s):  
Thymidylate Synthase ◽  
Active Site ◽  
Hydride Transfer ◽  
Transfer Step ◽  
Site Access

scholarly journals Hydride Transfer versus Hydrogen Radical Transfer in Thymidylate Synthase

2006 ◽  
Vol 128 (17) ◽  
pp. 5636-5637 ◽  
Author(s):  
Baoyu Hong ◽  
Majd Haddad ◽  
Frank Maley ◽  
Jan H. Jensen ◽  
Amnon Kohen
Keyword(s):  
Thymidylate Synthase ◽  
Hydride Transfer ◽  
Radical Transfer ◽  
Hydrogen Radical

scholarly journals Coupling of protein motions and hydrogen transfer during catalysis by Escherichia coli dihydrofolate reductase

2006 ◽  
Vol 394 (1) ◽  
pp. 259-265 ◽  
Author(s):  
Richard S. Swanwick ◽  
Giovanni Maglia ◽  
Lai-hock Tey ◽  
Rudolf K. Allemann
Keyword(s):  
Dihydrofolate Reductase ◽  
Active Site ◽  
Hydrogen Transfer ◽  
Isotope Effects ◽  
Hydride Transfer ◽  
Kinetic Isotope Effects ◽  
Reaction Rates ◽  
Protein Motions ◽  
Kinetic Isotope ◽  
Exponential Factors

The enzyme DHFR (dihydrofolate reductase) catalyses hydride transfer from NADPH to, and protonation of, dihydrofolate. The physical basis of the hydride transfer step catalysed by DHFR from Escherichia coli has been studied through the measurement of the temperature dependence of the reaction rates and the kinetic isotope effects. Single turnover experiments at pH 7.0 revealed a strong dependence of the reaction rates on temperature. The observed relatively large difference in the activation energies for hydrogen and deuterium transfer led to a temperature dependence of the primary kinetic isotope effects from 3.0±0.2 at 5 °C to 2.2±0.2 at 40 °C and an inverse ratio of the pre-exponential factors of 0.108±0.04. These results are consistent with theoretical models for hydrogen transfer that include contributions from quantum mechanical tunnelling coupled with protein motions that actively modulate the tunnelling distance. Previous work had suggested a coupling of a remote residue, Gly121, with the kinetic events at the active site. However, pre-steady-state experiments at pH 7.0 with the mutant G121V-DHFR, in which Gly121 was replaced with valine, revealed that the chemical mechanism of DHFR catalysis was robust to this replacement. The reduced catalytic efficiency of G121V-DHFR was mainly a consequence of the significantly reduced pre-exponential factors, indicating the requirement for significant molecular reorganization during G121V-DHFR catalysis. In contrast, steady-state measurements at pH 9.5, where hydride transfer is rate limiting, revealed temperature-independent kinetic isotope effects between 15 and 35 °C and a ratio of the pre-exponential factors above the semi-classical limit, suggesting a rigid active site configuration from which hydrogen tunnelling occurs. The mechanism by which hydrogen tunnelling in DHFR is coupled with the environment appears therefore to be sensitive to pH.

Investigation of Thymidylate synthase gene polymorphism in colon cancer patients

2012 ◽  
Vol 50 (05) ◽  
Author(s):  
A Schöller ◽  
A Kalmár ◽  
VÁ Patai ◽  
Z Nagy ◽  
B Barták ◽  
...  
Keyword(s):  
Colon Cancer ◽  
Gene Polymorphism ◽  
Cancer Patients ◽  
Thymidylate Synthase
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