Practice question
Question
In D₂O exchange, which proton gets replaced?
Explanation
Labile protons attached to nitrogen or oxygen exchange with deuterium in D2O through acid-base catalyzed mechanisms. Amide backbone NH in proteins exchanges at rates modulated by hydrogen bonding, solvent exposure, and structural stability, leading to disappearance of corresponding peak in proton spectrum after dissolution in deuterated solvent. Carbon-bound protons including aromatic, aliphatic, and C-alpha hydrogens are kinetically stable and remain visible. Monitoring amide signal decay therefore informs on protected secondary structures, membrane protein topology, and conformational dynamics relevant to folding and allosteric regulation.