Cytidine diphosphate

3TC-TP, CBV-TP, CBV, ¹⁵N₂¹³C-3TC, d₄-ABC, and emtricitabine-TP (FTC-TP) were obtained from Toronto Research Chemicals (North York, Canada). 3TC and ABC were provided by GlaxoSmithKline Inc. (Research Triangle Park, NC). Type XA acid phosphatase (EC 3.1.3.2) from sweet potatoes, guanosine, guanosine monophosphate (GMP), guanosine diphosphate (GDP), guanosine triphosphate (GTP), cytidine, cytidine monophosphate (CMP), cytidine diphosphate (CDP), and cytidine triphosphate (CTP) were purchased from Sigma Chemical Co. (St. Louis, MO). Sep-Pak QMA anion-exchange cartridges and OASIS HLB reverse-phase cartridges were purchased from Waters Corp. (Milford, MA). Potassium chloride (KCl) was purchased from JT Baker Co. (Phillipsburg, NJ). LC-MS grade (Optima) water (H₂O), acetonitrile (ACN), methanol (MeOH), acetic acid, ammonium hydroxide, and ammonium bicarbonate were purchased from Fisher chemicals (Fair Lawn, NJ). RPMI media 1640, phosphate buffered saline (PBS), Hanks’ Balanced salt solution (HBSS), and fetal bovine serum were purchased from Invitrogen (Gibco; Carlsbad, CA).

Luria Broth, ampicillin trisodium salt, L-arabinose, chloramphenicol, phenylmethylsulfonyl fluoride (PMSF), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), MgSO₄, adenosine triphosphate (ATP), deoxycytidine, and cytidine diphosphate (CDP) were purchased from Sigma-Aldrich. Isopropyl β-D-1-thiogalactopyranoside (IPTG) was purchased from GoldBio. DEAE and Q-Sepharose resins were obtained from GE Healthcare Life Sciences. Ni-NTA Sepharose resin was purchased from Qiagen. The primers for site-directed mutagenesis was obtained from Integrative DNA Technologies (IDT). BL21(DE3) E. coli competent cells were obtained from New England Biolabs (NEB). Tricarbonyl(1,10-phenanthroline)-(4-bromomethylpyridine)rhenium(I) hexafluorophosphate ([Re]-Br) was available from a previous study.^{22 (link)} [5-³H] CDP was purchased from ViTrax. Alkaline phosphatase (AP, calf intestine) was purchased from Roche. Thioredoxin (TR) and thioredoxin reductase (TRR) were available from a prior study.^{20 (link)}