title: Exploration of a potential difluoromethyl-nucleoside substrate with the fluorinase enzyme.
abstract: The investigation of a difluoromethyl-bearing nucleoside with the fluorinase enzyme is described. 5',5'-Difluoro-5'-deoxyadenosine 7 (F2DA) was synthesised from adenosine, and found to bind to the fluorinase enzyme by isothermal titration calorimetry with similar affinity compared to 5'-fluoro-5'-deoxyadenosine 2 (FDA), the natural product of the enzymatic reaction. F2DA7 was found, however, not to undergo the enzyme catalysed reaction with L-selenomethionine, unlike FDA 2, which undergoes reaction with L-selenomethionine to generate Se-adenosylselenomethionine. A co-crystal structure of the fluorinase and F2DA7 and tartrate was solved to 1.8Å, and revealed that the difluoromethyl group bridges interactions known to be essential for activation of the single fluorine in FDA 2. An unusual hydrogen bonding interaction between the hydrogen of the difluoromethyl group and one of the hydroxyl oxygens of the tartrate ligand was also observed. The bridging interactions, coupled with the inherently stronger C-F bond in the difluoromethyl group, offers an explanation for why no reaction is observed.
authors.affiliation: School of Chemistry and Biomedical Sciences Research Centre, University of St Andrews, North Haugh, St Andrews KY16 9ST, United Kingdom.
authors.forename: Stephen
authors.initials: S
authors.lastname: Thompson
authors.affiliation: School of Chemistry and Biomedical Sciences Research Centre, University of St Andrews, North Haugh, St Andrews KY16 9ST, United Kingdom.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: McMahon
authors.affiliation: School of Chemistry and Biomedical Sciences Research Centre, University of St Andrews, North Haugh, St Andrews KY16 9ST, United Kingdom.
authors.forename: James H
authors.initials: JH
authors.lastname: Naismith
authors.affiliation: School of Chemistry and Biomedical Sciences Research Centre, University of St Andrews, North Haugh, St Andrews KY16 9ST, United Kingdom. Electronic address: do1@st-andrews.ac.uk.
authors.forename: David
authors.initials: D
authors.lastname: O'Hagan
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry*; D002151:Calorimetry; D018360:Crystallography, X-Ray; D008715:Methionine / Q000737:chemistry; D010088:Oxidoreductases / Q000737:chemistry*; D012645:Selenomethionine / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; C068974:5'-deoxy-5'-difluoroadenosine; D012645:Selenomethionine; D008715:Methionine; D010088:Oxidoreductases; C495766:fluorinase; D000241:Adenosine
keywords: Difluoromethyl; Fluorinase; Isothermal titration calorimetry; Protein crystallography