[Nuclear magnetic resonance study of water in Nitella mucronata cells]

The properties of water contained in Nitella mucronata cells are examined by proton spin relaxation measurements. Two fractions of the cell water are observed. About 70% of cell water exhibits a longer relaxation time (T 1 congruent to 600 ms, T2 congruent to 300 ms), the exchange time of water molecules to and from hydration layer of macromolecules is equal to 0.06 ms and transforms into an ice-like state at --8 degrees C. About 30% of cell water exhibits a shorter relaxation time (T 1 congruent to 100 ms, T2 congruent to 50 ms), exchange of water molecules is not observed and there is no transformation into and ice-like state down to --30 degrees C. On the basis of the properties observed it could be concluded that the greater part of cell water behaves as "free water", while the lesser part of cell water may be regarded as a "bound water".