Deuterium oxide d

[3,4-¹³C₂]-D-glucose (97–98%) was obtained from Cambridge Isotopes Laboratories (Tewksbury, Massachusetts) and Omicron Biochemicals Inc. (South Bend, Indiana). [U-²H₇, U-¹³C₆]-D-glucose, deuterium oxide (D, 99.9%) and deuterochloroform (99.8%) were obtained from Cambridge Isotopes Laboratories (Tewksbury, Massachusetts). Ruthenium (10% on activated carbon, reduced) was obtained from Alfa Aesar. Silica gel (60 Å, 65 × 250 mesh) for flash chromatography was obtained from Sorbent Technologies (Norcross, Georgia). The free radical polarizing agent trityl OX063 was obtained from Oxford Instruments Molecular Biotools (Tubney Woods, United Kingdom). Other reagents and solvents were obtained from Sigma-Aldrich (St. Louis, Missouri). All reagents and solvents were used without further purification.

EGCG from green tea (458.4 Da, ≥95% purity) was ordered from Sigma-Aldrich (St. Louis, MO, USA). CypD was overexpressed and purified. Briefly, the CypD coding sequence was inserted downstream of the Thermoanaerobactor tencongenesis ribose-binding protein (RBP) gene of the pET41 plasmid, fused to a nucleotide sequence containing the HRV3C protease cleavage site, with a His tag at the 3′ end of the CypD gene. The plasmid was transformed into E. coli BL21 (DE3). The strain was induced to express the protein using IPTG. Then, protein was purified using a Ni²⁺-NTA column and lysed overnight using HRV3C protease (4 °C) and recovered using Ni²⁺-NTA and S75 size exclusion chromatography with a final purity of >95% as judged by SDS-PAGE. SPR CM5 sensor chip and amine coupling kit were obtained from GE Healthcare Bio-Sciences AB (Uppsala, Sweden). Deuterium oxide (D, 99.9%) was purchased from Cambridge Isotope Laboratories Inc (Tewksbury, MA, USA).

Triglycine peptide (GGG) was purchased from Chem-Impex (cat# 04555) and diglycine peptide (GG) was obtained from Sigma (#G1002). Ammonium chloride (15N, 99%, cat# NLM-467) and D-glucose (U-13C6, 99%, cat# CLM-1396) for isotopic labeling were purchased from Cambridge Isotope Laboratories. Deuterium oxide (D, 99.9%) for NMR recordings was also obtained from Cambridge Isotope Laboratories (cat# DLM-4). Water used in biological procedures or as a reaction solvent was purified using a Milli-Q Advantage A10 system (Millipore). All other chemicals and reagents were obtained from commercial sources and used without further purification.