[Study of lysozyme by a spin-label method in the 2-mm range]

Two millimeter range ESR-spectroscopy was used to measure the values of magnetic resonance parameters of egg lysozyme samples modified with nitroxyl label 4-(iodine-acetamide)-2,2,6,6-tetramethylpiperidine-1-oxyl by hist-15 residue. It has been shown that in a lyophilic sample the spin label forms a hydrogen bond with the protein group and when the sample is moistened--with water molecules. Temperature changes of the pattern of ESR line are analysed. It is concluded that in the moistened samples within 230-320 K the nitroxyl fragment of the label gets engaged in anisotropic movement with preferable rotation around Z-axis of N-O. fragment with anisotropy coefficient 5 and mean correlation time tau congruent to 5 X 10(-7) divided by 5 X 10(-8) c.