Publisher Summary This chapter describes many of the techniques employed to study water–macromolecules interactions, their general usefulness, points out areas of mutual support and contradiction. The chapter also presents hydration of other macromolecules and the hydration of small molecules. Four broadly based approaches to operational definitions of hydration include—(1) preferential hydration, (2) hydrodynamic hydration, (3) structural hydration, and (4) low temperature hydration. The use of high resolution X-ray and neutron diffraction data on protein crystals provides an independent approach for estimation of hydration. The chapter presents several proposals for predicting protein hydration based on the amino acid composition of the protein; however, the two main questions concerned include—whether ionic groups are more hydrated than other polar groups, and whether the amide and peptide functions are hydrated or not. Low pH, and to a much smaller degree, high pH should dehydrate proteins. Intermolecular association via ionic mechanisms should be strongly dehydrating; whereas hydrophobic interactions should not have much effect on hydration levels. Although, there is a presumption that both the enthalpy and the entropy are negative for the process of adding water molecules to isolated proteins, which are maintained in their native conformations, but there is no unequivocal evidence for this.

Hydration of Proteins and Polypeptides

https://www.cell.com/biophysj/pdf/S0006-3495(77)85550-1.pdf

A theory of fluorescence polarization decay in membranes.

Among the Various methods for characterizing macromolecules in solution, hydrodynamic techniques play a major role. Since the advent of the ultracentrifuge and the development of viscometric apparatus, sedimentation coefficients and intrinsic viscosities have been extensively used to learn about the size and shape of synthetic and biological polymers. More recently, refined techniques such as quasielastic light scattering, transient electric birefringence and fluorescence anisotropy decay have made it possible to obtain in a simple and rapid way quantitative information of high precision on the translational and rotational brownian dynamics of dissolved macromolecules.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033583500002080

Hydrodynamic properties of complex, rigid, biological macromolecules: theory and applications.

Fluorescence resonance energy transfer and fluorescence polarization anisotropy are used to investigate single molecules of the enzyme staphylococcal nuclease. Intramolecular fluorescence resonance energy transfer and fluorescence polarization anisotropy measurements of fluorescently labeled staphylococcal nuclease molecules reveal distinct patterns of fluctuations that may be attributed to protein conformational dynamics on the millisecond time scale. Intermolecular fluorescence resonance energy transfer measurements provide information about the dynamic interactions of staphylococcal nuclease with single substrate molecules. The experimental methods demonstrated here should prove generally useful in studies of protein folding and enzyme catalysis at single-molecule resolution.

https://www.pnas.org/content/pnas/96/3/893.full.pdf

Single-molecule fluorescence spectroscopy of enzyme conformational dynamics and cleavage mechanism

The rotational correlation times of individual asphaltene molecules have been determined using fluorescence depolarization techniques, addressing an active, long-standing controversy. Using simple ...

Asphaltene Molecular Size and Structure

Reexamination of the theory of fluorescence time dependence owing to rotational diffusion of rigid macromolecules reveals deficiencies or hidden restrictions in each of the previous treatments. The correct master equation has five exponential decay terms, with preexponential factors that depend upon the diffusion constants and, in a completely symmetrical fashion, upon the orientations of absorbing and emitting dipoles.

https://www.pnas.org/content/pnas/69/6/1392.full.pdf

G. G. Belford

Papers

Dynamics of Fluorescence Polarization in Macromolecules