Picosecond relaxations in hydrated lysozyme observed by mm-wave spectroscopy.

Dielectric absorption measurements at mm-wave frequencies (50 GHz. . . 150 GHz) are reported for lysozyme at different hydration levels. The measurements were extended over the temperature range from liquid helium to room temperature using the untuned cavity technique. For dried lysozyme (water content less than or equal to 0.5%, w/w) a nearly linear increase with frequency and an exponential increase with temperature of the absorption coefficient is observed between 50 K and 300 K. This frequency and temperature dependence is described by relaxation processes in asymmetric double-well potentials with relaxation times in the picosecond range. Hydration yields a nearly frequency-independent contribution to the absorption, which arises only at temperatures above 120 K. The frequency independence indicates relaxation rates for the bound water that are small compared to mm-wave frequencies. Thereby the contribution of bound water can clearly be distinguished from the fast intrinsic processes. An assignment of these picosecond relaxations to the NH . . . OC hydrogen bond of the peptide backbone is suggested.

A non-thermal effect of millimeter wave radiation on the puffing of giant chromosomes.

A non-thermal influence of millimeter wave radiation (swept in frequency from 64.1 GHz to 69.1 GHz, sweeptime 6 s, and with stabilized frequencies of 67.200 +/- 0.001 GHz and 68.200 +/- 0.001 GHz, power density less than or equal to 6 mW/cm2) on the puffing of giant chromosomes of the midge Acricotopus lucidus (Diptera, Chironomidae) was found. The effect is manifested as a reduction in size of a specific puff that expresses genes for a secretory protein. The non-thermal nature of the effect was proved by experiments in which the sham-exposed sample was warmed up by 2.5 degrees C which is more than the eight-fold microwave induced temperature increase of less than or equal to 0.3 degrees C. Concerning the very low photon energy of mm-waves compared to the thermal energy kT, it seems likely that the coherence of the radiation is essential for the observed effect.