NMR spectra were recorded in a 9:1 H2O/D2O mixture or 99.95%
D2O (after deuterium-exchange by freeze-drying from 99.9% D2O)
at 35 C using a Bruker Avance II 600-MHz spectrometer, and the
Bruker TopSpin 2.1 program was used to acquire and process the
NMR data. Internal sodium 3-trimethylsilylpropanoate-2,2,3,3-d4
(dH 0, dC 1.6) was used as reference for calibration. The mixing