Hydride transfer versus hydrogen radical transfer in thymidylate synthase.
نویسندگان
چکیده
The nature of a H-transfer in the thymidylate synthase catalyzed reaction was investigated by comparison of the wild-type enzyme with the W80M mutant. The nature of the H-transfer was not affected, as indicated by intrinsic isotope effects and their temperature dependence. These findings support a single-step hydride transfer instead of a two-step radical transfer.
منابع مشابه
Investigation on chemical steps of thymidylate synthase catalyzed reaction
Thymidylate synthase (TS) catalyzes the reductive methylation of 2’deoxyuridylate (dUMP) with cofactor 5,10-methylene-5, 6, 7, 8-tetrahydrofolate, forming thymidine monophosphate (dTMP) and 7, 8-dihydrofolate. The reaction pathway is comprised of at least seven covalent bond cleavage or formation, therefore, it is a very complex system for scientists to explore the mechanistic details of this r...
متن کاملConcerted versus Stepwise Mechanism in Thymidylate Synthase
Thymidylate synthase (TSase) catalyzes the intracellular de novo formation of thymidylate (a DNA building block) in most living organisms, making it a common target for chemotherapeutic and antibiotic drugs. Two mechanisms have been proposed for the rate-limiting hydride transfer step in TSase catalysis: a stepwise mechanism in which the hydride transfer precedes the cleavage of the covalent bo...
متن کاملTryptophan 80 and leucine 143 are critical for the hydride transfer step of thymidylate synthase by controlling active site access.
Mutant forms of thymidylate synthase (TS) with substitutions at the conserved active site residue, Trp 80, are deficient in the hydride transfer step of the TS reaction. These mutants produce a beta-mercaptoethanol (beta-ME) adduct of the 2'-deoxyuridine-5'-monophosphate (dUMP) exocyclic methylene intermediate. Trp 80 has been proposed to assist hydride transfer by stabilizing a 5,6,7,8-tetrahy...
متن کاملEnzymatic H Transfers: Quantum Tunneling and Coupled Motion from Kinetic Isotope Effect Studies
Many hydrogen transfer processes exhibit nonclassical behavior due to inherent quantum mechanical properties of the hydrogen. Investigation of various enzymes under physiological conditions indicates that hydrogen transfer processes often show significant quantum mechanical behavior. Traditionally, this phenomenon was treated in terms of a tunneling correction to classical or semiclassical mode...
متن کاملA remote mutation affects the hydride transfer by disrupting concerted protein motions in thymidylate synthase.
The role of protein flexibility in enzyme-catalyzed activation of chemical bonds is an evolving perspective in enzymology. Here we examine the role of protein motions in the hydride transfer reaction catalyzed by thymidylate synthase (TSase). Being remote from the chemical reaction site, the Y209W mutation of Escherichia coli TSase significantly reduces the protein activity, despite the remar...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Journal of the American Chemical Society
دوره 128 17 شماره
صفحات -
تاریخ انتشار 2006