Correlation Time Of Water Research Articles

Vibrational couplings and line shapes of CN stretchings in aqueous KOCN-KSCN binary systems in two-dimensional layers

Infrared spectra in the region of the CN stretchings of aqueous KOCN-KSCN binary systems as well as KOCN or KSCN pure solutions are observed in the gel phase of the mono-palmitin-water system, where two-dimensional water layers are formed. Similar observations are carried out for the systems with sodium dodecyl sulphate (SDS). The spectra are analyzed on the basis of a linear response function with mechanical and damping coupling constants. In the KOCN or KSCN pure solutions the band widths depend slightly on SDS and differ considerably with those in the isotropic solutions, clarifying the difference in the correlation time of water between the two-dimensional and the isotropic systems. In the KOCN–KSCN binary systems the relative intensities of the OCN − with SCN − ions depend considerably on SDS. This is explained in terms of the orientation of OCN − ions, which prefer to orient parallel to the water-lipid boundary. The mechanical coupling constant is somewhat larger than that expected from two-dimensional layers. This results in the effects of both the reduction of a dielectric constant of water and multiple reflections of an electric field on the water-lipid boundary.

DYNAMIC EVALUATION OF THE DEHYDRATION RESPONSE CURVES OF FOODS CHARACTERIZED BY A POULTICE-UP PROCESS USING A FISH-PASTE SAUSAGE. I. DETERMINATION OF THE MECHANISMS FOR MOISTURE TRANSFER

In order to discern the mechanism for the transfer of moisture in foods as they are drying, the pore structure of food and the distribution of moisture in food matrices were studied in detail by using a fish-paste sausage that was prepared with various contents ofmo isture (W 0). A uniform distribution ofmois ture was achieved with a poultice-up process. The void fractions (Vf ) that occurred as a result ofchanges in the pore structure of the food were evaluated from a graphical analysis of SEM photographs on a cross-sectional observation ofthe sausage. The Vf -values obtained changed drastically depending on the W0 and were classified into two regions: I (W 0 > 100%-d.b.), which gave Vf = 0.10 ± 0.08, and II (W 0 < 100%-d.b.), which gave Vf = 0.24 ± 0.05 at a drying temperature of 35°C. For the analysis ofmois ture state, the temperature-programmed desorption (TPD) profiles and the correlation time ofwater protons evaluated from nuclear magnetic resonance (NMR) were effectively used. The results produced three states ofmois ture: weakly and strongly restricted water at Region I and gaseous water at Region II.

Mobility of water in biological systems studied by17O NMR via multiple-quantum filtered relaxation analysis

Multiple-quantum filtering NMR sequences were used to study the multiexponential relaxation behaviour of H217O in the presence of macromolecules. By this means, the fraction and the correlation time of water in slow motion, or ‘bound’ water, were determined, in addition to the relaxation time of bulk water in the extreme narrowing limit. Experiments were carried out on aqueous solutions of bovine serum albumin, hen egg white lysozyme and intact human red blood cells in which intracellular water properties were studied. The small fraction of bound water of less than 1% seems to correspond to ‘strongly bound’ water, whereas the behaviour of bulk water was different from that of pure water and may be due to weak (or transient) interactions with macromolecules. The experiments and the data analysis gave reproducible results which support the idea that diverse samples could be studied in this way in order to help understand their water properties. © 1997 John Wiley & Sons, Ltd.

Mobility of water in biological systems studied by 17O NMR via multiple‐quantum filtered relaxation analysis

Multiple-quantum filtering NMR sequences were used to study the multiexponential relaxation behaviour of H217O in the presence of macromolecules. By this means, the fraction and the correlation time of water in slow motion, or ‘bound’ water, were determined, in addition to the relaxation time of bulk water in the extreme narrowing limit. Experiments were carried out on aqueous solutions of bovine serum albumin, hen egg white lysozyme and intact human red blood cells in which intracellular water properties were studied. The small fraction of bound water of less than 1% seems to correspond to ‘strongly bound’ water, whereas the behaviour of bulk water was different from that of pure water and may be due to weak (or transient) interactions with macromolecules. The experiments and the data analysis gave reproducible results which support the idea that diverse samples could be studied in this way in order to help understand their water properties. © 1997 John Wiley & Sons, Ltd.

Determination of the Bound Water Fraction in Cells and Protein Solutions Using17O–Water Multiple-Quantum Filtered Relaxation Analysis

Multiple-quantum filtering NMR sequences were used to study the multiexponential relaxation behavior of H217O in the presence of macromolecules. By this means, the fraction and the correlation time of water in slow motion, or “bound” water, were determined, as well as the relaxation time of bulk water in the extreme-narrowing limit. Aqueous solutions of bovine serum albumin and intact human red blood cells were studied. The small fraction of bound water of less than 1% appeared to correspond to “strongly bound” water, whereas the behavior of bulk water was different from pure water and was interpreted as being due to weak (or transient) interactions with macromolecules. The experiments and the data analysis appeared to be reproducible, which suggests that diverse samples might be studied this way and thus help define the properties of water in these systems.

The application of perturbed directional correlation of gamma rays to the study of protein-metal interactions.

Several branches of nuclear spectroscopy—magnetic resonance and the Mossbauer effect in particular—have been the subject of considerable interest to obtain structural and motional information about biological macromolecules. Recently, a third technique— perturbed gamma-gamma directional correlation—is being tested for the study of rotational correlation times, internal rotations and conformational changes in biological macromolecules. When two gamma rays from a radioactive nucleus are emitted in a cascade and detected with a coincidence spectrometer, the coincidence counting rate depends strongly on the angle between their directions of propagation. This directional correlation can be perturbed by the interaction of the nucleus with fields existing in macromolecules. A study of such perturbed directional correlation (PDC) has the potential to provide information on protein-metal interactions. The use of a radioactive nucleus as a rotational tracer to label macromolecules offers the possibility of obtaining information on protein structure with the sensitivity and instrumental simplicity of radioactive tracer techniques. Work to date has centered on measurement of internal electric field gradients of metalloproteins, molecular correlation times and the correlation time of water associated with proteins. This paper is a brief review of the theory and experimental technique of perturbed directional correlation of gamma rays in comparison to Mossbauer spectroscopy and the methods of magnetic resonance. Particular emphasis will be placed on the isotopes which can be used in PDC especially those which may occupy sites in biological macromolecules.