Both the theoretical material and experimental data presented in this book clearly demonstrate the significant progress that has recently been made in applying biophysical labeling methods to molecular biology. This progress resulted from interdisciplinary cooperation. Biochemistry and biophysics formulated up-to-date structural, dynamic, and functional problems to be solved. Advances in synthetic chemistry provided researchers with a wide assortment of labels and probes and paved the way for specific modifications of certain portions of biological objects.

Let us summarize the main advances, possibilities, and limitations of biophysical labeling methods.

Molecular dynamics of biosystems in the areas of spin, fluorescent, triplet, and Mössbauer labels can be investigated within a wide range of correlation times (tc = 102–10-10s) and amplitudes. The values of the electron spin relaxation parameters, 1/Tle and 1/T2e, of spin labels and the probability of recoilless absorption of γ-quanta (ƒ′) reflect the intensity of the high-frequency low-amplitude phonon processes. The parameters of Mössbauer spectra (the line width), ESR spectra (the line form, saturation transfer), and luminescence spectra (the relaxation shift, depolarization) are dependent on the processes of vibration, wobbling, and rotational diffusion of the label, as well as orientational relaxation of surrounding dipoles. The same parameters can be sensitive to such local properties as polarity, electric potential, ability to form the hydrogen bond and participate in redox reactions.