400 MHz NMR Study of Isotope Effects on Albumin in H₂O/D₂O Solutions

Chemical shift measurements were performed for several percentages of H₂O added to D₂O, in several H₂O/D₂O mixtures without and with a single concentration of albumin, and also in a mixture of 0.1H₂O/0.9D₂O containing increasing concentrations of albumin. The chemical shifts of pure mixtures decreases with increasing fraction of pure water. This is closely related to isotope effects. The chemical shift corrected for isotope effects increases with percentage of H₂O. The chemical shift obtained for the mixture of 0.1H₂O/0.9D₂O increases with increasing concentration of albumin. These increments are consistent with fast chemical exchange in H₂O/D₂O mixture. In conclusion, present study reveals the presence of isotope effect on albumin in H₂O/D₂O solutions, and demonstrates fast chemical exchange in D₂O solutions with albumin in a different way.