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Protein motions during catalysis by dihydrofolate reductases

Protein motions during catalysis by dihydrofolate reductases

Allemann, Rudolf K., Evans, Rhiannon M., Tey, Lai-hock, Maglia, Giovanni, Pang, Jiayun, Rodriguez, Robert, Shrimpton, Paul J. and Swanwick, Richard S. (2006) Protein motions during catalysis by dihydrofolate reductases. Philosophical Transactions of the Royal Society B: Biological Sciences, 361 (1472). pp. 1317-1321. ISSN 0962-8436 (Print), 1471-2970 (Online) (doi:10.1098/rstb.2006.1865)

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Abstract

Dihydrofolate reductase (DHFR) maintains the intracellular pool of tetrahydrofolate through catalysis of hydrogen transfer from reduced nicotinamide adenine dinucleotide to 7,8-dihydrofolate. We report results for pre-steady-state kinetic studies of the temperature dependence of the rates and the hydrogen/deuterium-kinetic isotope effects for the reactions catalysed by the enzymes from the mesophilic Escherichia coli and the hyperthermophilic Thermatoga maritima. We propose an evolutionary pattern in which catalysis progressed from a relatively rigid active site structure in the ancient thermophilic DHFR to a more flexible and kinetically more efficient structure in E. coli that actively promotes hydrogen transfer at physiological pH by modulating the tunnelling distance. The E. coli enzyme appeared relatively robust, in that kinetically severely compromised mutants still actively propagated the reaction. The reduced hydrogen transfer rates of the extensively studied Gly121Val mutant of DHFR from E. coli were most likely due to sterically unfavourable long-range effects from the introduction of the bulky isopropyl group.

Item Type: Article
Uncontrolled Keywords: hydrogen transfer, kinetic isotope effects, protein dynamics, catalysis, enzymes
Subjects: Q Science > Q Science (General)
Faculty / Department / Research Group: Faculty of Engineering & Science > Department of Pharmaceutical, Chemical & Environmental Sciences
Related URLs:
Last Modified: 17 Oct 2016 09:12
Selected for GREAT 2016: None
Selected for GREAT 2017: None
Selected for GREAT 2018: None
URI: http://gala.gre.ac.uk/id/eprint/10622

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