β,γ-CXY dNTP analogues 1 are useful chemical probes to investigate DNA polymerase catalysis and fidelity. Nonequivalent (X ≠ Y) substituents on the β,γ-carbon generate diastereomer pairs potentially exhibiting different interactions within the chiral environment of the polymerase active site. Conventional synthetic methods generate a mixture of both possible diastereomers, limiting their use as stereoprobes. We recently reported the first route to the individual (S)- and (R)-diastereomers of β,γ-CHCl dGTP and β,γ-CHF dGTP, based on a novel bisphosphonate synthon equipped with an (R)-methyl mandelate auxiliary. This method has now been used to prepare the individual β,γ-CHX dATP (X= F, Cl) diastereomers (1a-d). Because the final step (removal of the chiral auxiliary by (Pd/C) hydrogenolysis) is incompatible with both the cytosine ring and the β,γ-CHBr moiety, this route did not give access to the corresponding dCTP diastereomers (1e-j) which were obtained using (R)-(+)-α-ethylbenzylamine as the chiral auxiliary, with replacement of the reductive step by photochemical deprotection. The first examples of individual β,γ-monomethyl dNTP diastereomers (dATP) (1k,1l) were prepared using an (R)-(-)-phenylglycine auxiliary. All stereoisomers were distinguishable by their NMR spectra. Presteady-state kinetics with pol η and pol β showed that kpol (R) &gt; kpol (S) with stereopreferences of 6.3 (1a,1b) and 2.0 (1c,1d) (pol η) and 3.8 (1e,1f) and 6.3 (1g-1h) (pol β), revealing CHX chirality-dependent effects on the TS energy during turnover in the active sites of pol η and β.

β,γ-CHX (X: CH3, F, Cl, Br) dATP and dCTP diastereomers: Synthesis, discrete NMR signatures and substrate stereochemistry with DNA polymerase η and β

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.