Pulsed nuclear magnetic resonance studies were carried out on small ice particles with large surface to volume ratios to investigate the so-called quasi-liquid layer (Q.L.L.) on an ice surface. The temperature dependence of features of the NMR spectra and dynamical properties such as the correlation the for rotational motion and the self diffusion coefficient of the Q.L.L. were described. The frequency of the rotational molecular motion and the self diffusion coefficient were larger than those of bulk ice by about five orders and by two orders, respectively

Some physico-chemical parameters of frozen-thawed enzyme proteins were examined to investigate the mechanism of protein denaturation by freeze-thawing. The enzymatic activity and the conformational parameters of fibrous proteins, such as myosin B, myosin A, H-and L-meromyosin, decreased depending on the freezing temperature and the cooling rate. On the contrary, the conformational parameters of globular proteins",such as G-actin and catalase, did not change, in spite of the fact that the decrease of the enzymatic activity depends on the freezing temperature.These results suggest that the freeze-thawing causes a partial unfolding of the helical structure in the fibrous proteins corresponding to the freezing conditions, but does not cause such a conformational change in the globular proteins. It might be said, therefore, that the molecular conformation is more stable against freeze-thawing in globular protein than in the fibrous protein.The mechanism of the denaturation by freezing was discussed further in relation to the behavior of hydration water during the freezing process.

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