Cover: Deoxycytidine kinase (dCK) can phosphorylate nucleosides of both D- and L- chirality. This has medicinal ramifications, as anti-HIV nucleoside analogs of opposing chirality to physiological D-nucleosides, such as 3TC, require conversion to their triphosphorylated form—the initial phosphorylation step being catalyzed by dCK—to achieve pharmacological activity. Top right is a ribbon diagram of a dCK monomer (helices in purple, strands and coils in cyan) with the nucleoside analog 3TC (left) and ADP (right) rendered as ball-and-stick objects. Lower left is a magnified view of a 3TC molecule—an L-nucleoside—(nitrogens blue, oxygens red, sulfur orange, and carbons yellow) with its enantiomeric D-form reflection in the mirror. Both the L- and D- enantiomers are substrates for dCK, but the L-form has superior anti-HIV properties. For further information see the paper by Sabini et al. in this issue [Nucleic Acids Res. (2007) 35, 186–192].
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