Deuterium oxide

All chemicals and reagents used were of analytical grade. Potassium dihydrogen phosphate (99%, KH₂PO₄), deuterium oxide (99.9%, D₂O), methanol-d₄ (>99.8%, MeOD), and methanol were purchased from VWR (Radnor, PA, United States). Sodium deuteroxide 40% w/v solution in D₂O (99.5%, NaOD) was obtained from Alfa Aesar (Kandel, Germany). 3-(Trimethylsilyl) propionic-2,2,3,3-d₄ acid sodium salt (99%, TMSP) was obtained from Sigma-Aldrich (St. Louis, MO, United States). A Millipore Direct-Q^® 3 UV Water Purification System (Millipore Corp., Bedford, MA, United States) or (Merck KGaA, Darmstadt, Germany) for ultrapure water was used throughout the study.

β-cyclodextrin (BCyD) was the product of Cyclolab Ltd., Budapest, Hungary. Fenbufen (γ-oxo-(1,1′-biphenyl)-4-butanoic acid), fenoprofen calcium salt (calcium (±)-2-(3-phenoxyphenyl)propanoate dihydrate, and nimesulide (N-(4-nitro-2-phenoxyphenyl)methanesulfonamide) were purchased from Sigma-Aldrich/Merck Group, Budapest, Hungary. Bifonazole ((RS))-1-[phenyl(4-phenylphenyl) methyl]-1H-imidazole) was the product of Sandoz, Budapest, Hungary. Deuterium oxide (D₂O, 99.96% D) and sodium-deuteroxide (NaOD 40% w/w solution in D₂O, 99.5% D) were the products of VWR Chemicals, Leuven, Belgium and Alfa Aesar Chemicals, Kandel, Germany, respectively.

Alcohol
dehydrogenase (ADH, baker’s
yeast), glutamate dehydrogenase (GDH, beef liver), and d,l-phosphonoalanine were from Sigma. 2-Aminoethylphosphonate
(AEP) was from Wako chemicals. Triethanolamine (TEA), pyridoxal 5′-phosphate
(PLP), and bovine serum albumin (BSA) were from Sigma-Aldrich. NADH
was from Alfa Aesar. TLC plates (silica gel 60 F₂₅₄) were
from Merck Millipore. Deuterium oxide was from VWR International,
and deuterated trimethylsilyl propionic acid (TSP) from Stohler Isotope
Chemicals. All other reagents were from Fluka or Sigma-Aldrich.
Racemic HAEP was synthesized beginning from vinylphosphonic acid,
as described in ref (15 (link)); the S and R enantiomers of HAEP
were also prepared by methods described in the same publication.^{15 (link)}