Water in cells

Younis, H.M., Boyer, J.S. Govindjee (1979). Conformation and activity ofchloro-plast coupling factor exposed to low chemical potential of water in cells. Biochimica et Biophysica Acta, 548, 328-40. 

Mavroides JG, Tchemev DI, Kafalas JA, Kolesar DP (1975) Photoelectrolysis of water in cells with Ti02 anodes. Mater Res Bull 10 1023-1030... 

Similar results of photoelectrolysis of water in cells with n-type SrTi03 single-crystal anode and platinized Pt cathode were reported around the same time in a preliminary communication by Mavroides et al. [53] who measured the maximum quantum efficiency... 

Mavroides, G., Kafalas, J.A., and Kolesar, D.F., Photoelectrolysis of water in cells with SrTiOs anodes, Appl. Phys. Lett., 28,241,1976. 

Photoelectrolysis of water in cells with SrTiOs anodes. Apl Phys Lett 28 241-243... 

K. Striking is the broad distribution of jump times of water in cell walls coextending from times of liquid water to ice. We can compare water in cell walls with supercooled water with a broad scale of mobilities. The reduction of the apparent T may be induced by the interaction water/mucopolysaccharid groups. Water in charcoal with mean pore radius of 13 A shows a broader distribution of t but with a... 

The platelet preparation is mixed (depending on the volume of sample and the cell count) with sufficient methanol (usually added first) and chloroform to make a final mixture of chloroform-methanol-water (based on water in cell sample) of 1 2 0.8 (v/v). This mixture is then mixed well and allowed to stand for 25-30 min at room temperature in a dark cabinet (or shielded with aluminum foil) to allow extraction of the lipids from the cells. Then the mixture is centrifuged at 2000g for 10 min. A single-phase, clear-colored supernatant will result. This is carefully removed from the pellet and saved, because it represents the total lipid extract. Though a second extraction of the pellet with chloroform-methanol-water (1 2 0.8, v/v) can be done, it is usually not necessary. 

Photoelectrolysis of Water in Cells with Ti02 Anodes Both single crystal and polycrystalline TiCte used and external quantum efficiency measured. 226... 

Photoelectrolysis of Water in Cells with SrTiCh Anodes. Maximum quantum efficiency at zero bias (10% at hv = 3.8 eV) found to be -an order of magnitude higher than TiCh. 388... 

A loss of water from plant shoots—indeed, sometimes even an uptake — occurs at cell-air interfaces. As we would expect, the chemical potential of water in cells compared with that in the adjacent air determines the direction for net water movement at such locations. Thus we must obtain an expression for the water potential in a vapor phase and then relate this P to for the liquid phases in a cell. We will specifically consider the factors influencing the water potential at the plant cell-air interface, namely, in the cell wall. We will find that vFcel1 wal1 is dominated by a negative hydrostatic pressure resulting from surface tension effects in the cell wall pores. 

Finally, the question of the structure of biological water is one of far-reaching importance. Some workers in the last few decades have suggested that water in biological systems is special but our answer is that this special structure is so readily explicable that no mystery exists. Biological cells are sized on the micron scale and contain much soiid material. The surface-to-volume ratio inside such cells is very large. Most of the waters in cells are in fact surface waters. In this sense, biologicai water is special but only because it has lost the netted-up properties of bulk water and adopted the individual two-dimensional structure of water at all surfaces. 

Water held in the interstices of solids, as liquid covering the surface and as free water in cell cavities, is subject to movement by gravity and capillarity, provided passageways for the continuity of flow are present. Water flow due to a capillarity applies to water not held in solution and to all water above the fiber saturation point (as in textiles, paper, and leather) and to all water above the equilibrium moisture concentration at atmospheric saturation as in fine powers and granular solids, such as paint, pigments, minerals, clays, soil, and sand (H6). 

Chaplin M. Do we underestimate the importance of water in cell biology Nature Reviews Mol. Cell Biol. 2006 7 861-866. 

Symmetrical application of magnetic field gradients around the refocusing pulse in a spin echo will refocus the signal from static molecules. However, microscopic molecular motion (Brownian motion) will cause dephasing of individual magnetic moments to a degree which is dependent on the freedom of the molecular motion of the water in cells. Freedom of the molecular motion... 

Figure 24 shows curves of Qi, AG, and TAS plotted against wood moisture content. All energy terms are negative (heat is given off) when wood takes up water from the liquid state. The decrease in entropy indicates that bound water is more ordered than liquid water, in analogy to the greater order of water in ice compared with the liquid state. As the moisture content approaches fiber saturation the distinction between liquid water and water in wood decreases toward zero. However, even above fiber saturation the water in cell cavities may be different from ordinary liquid water because of capillary forces and/or dissolved materials. 

All cellular processes take place in aqueous solution, and it is essential to understand the properties of water in order to understand biological processes. This statement comes from one of the most recent textbooks on molecular cell biology. Sadly, but common to such texts, what follows is but a brief description of the ordinary liquid. Its physical properties and peculiarities are described, but the reader is given no information about the nature and role of water at interfaces such as in the environment of the cell. In short, from such descriptions one must infer that water in cells is just the same as water in a beaker or a cup of tea—that water is water. 

Until the last 30 or 40 years, relatively little effort had been made to elucidate in any detail the structure and function of water in cells. Fortunately, however, the situation is changing, and a growing body of evidence already suggests that at least some of the water in cells differs in its properties (such as density, viscosity, dielectric behavior, and heat capacity) from the ordinary bulk liquid. The lack of suitable measurement techniques has hampered the attainment of a more definitive description of intracellular water, nonetheless, much about it now appears within our grasp. 

Evidence for Vicinal Water in Cells Nature of Bulk and Cell-Associated Water... 

The purpose of this chapter and the next is two-fold first, to gather and review some of the evidence for structural changes in water and aqueous solutions adjacent to an interface, and secondly, to illustrate how these structural effects are manifested in the functioning of cells. What is addressed is not only the structure of bulk water but also the unique aspects of water in cells or near any surfaces. We refer to water near interfaces as vicinal water after the Latin word for neighbor. It is the vicinal water that suggests itself as the most likely site for most of the intermediary metabolism in living cells. 

One of the most characteristic features of vicinal water is the occurrence of anomalies in its properties as a function of temperature. These anomalous changes occur approximately 15°C apart, i.e., near 14-16°, 29-32°, 44-46°, and 59-62°C. The changes at these transition temperatures are quite abrupt and in many cases very pronounced. The effects of vicinal water and the thermal transitions on cell biology are frequently dramatic and surprising. The functional role of vicinal water in cell biology is the subject of the next chapter. 

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