Rotational and translational water diffusion in the hemoglobin hydration shell: dielectric and proton nuclear relaxation measurements.

The dynamic properties of water in the hydration shell of hemoglobin have been studied by means of dielectric permittivity measurements and nuclear magnetic resonance spectroscopy. The temperature behavior of the complex permittivity of hemoglobin solutions has been measured at 3.02, 3.

Structural fluctuations and conformational entropy in proteins: entropy balance in an intramolecular reaction in methemoglobin.

The reversible intramolecular binding of the distal histidine side chain to the heme iron in methemoglobin is of special interest due to the very large negative reaction entropy which overcompensates the large reaction enthalpy. It may be considered as a prominent example of the ability of proteins (including enzymes) to provide global entropy in a local process. In this work new experiments and model calculations are reported which aim at finding the structural elements contributing to the reaction entropy.

A new method for the determination of the permittivity of small samples in the microwave range and its application to hemoglobin single crystals.

A cavity perturbation method for the absolute determination of the complex permittivity of small samples in the microwave range is developed and tested. Samples with volumes less than 0.4 mm3, for example protein powder or single crystals of macromolecules, may be investigated in a temperature range between 180 and 300 K, using this method.

Conformational transition of aquomethemoglobin: intramolecular histidine E7 binding reaction to the heme iron in the temperature range between 220 K and 295 K as seen by EPR and temperature-jump measurements.

Temperature-dependent EPR and temperature-jump measurements have been carried out, in order to examine the high-spin to low-spin transition of aquomethemogobin (pH 6.0). Relaxation rates and equilibrium constants could be determined as a function of temperature.

A new method for absolute determination of radical concentrations of EPR.

A new method for precise absolute determination of radical concentrations by EPR is described. Cavity quality factors, cavity mismatching, power levels and receiver characteristics do not have to be measured. The measurement of radical concentration is reduced to the determination of geometrical factors, the area under the EPR absorption curve, the LF modulating field strength and a frequency change.