Hydration of proteins

Although the emphasis in these last chapters is certainly on the polymeric solute, the experimental methods described herein also measure the interactions of these solutes with various solvents. Such interactions include the hydration of proteins at one extreme and the exclusion of poor solvents from random coils at the other. In between, good solvents are imbibed into the polymer domain to various degrees to expand coil dimensions. Such quantities as the Flory-Huggins interaction parameter, the 0 temperature, and the coil expansion factor are among the ways such interactions are quantified in the following chapters. 

Differential hydration of proteins has been little exploited as a selectivity factor in ion exchange, but it is simple to evaluate and can produce useful results. This technique relies on the preferential exclusion of certain solutes from protein surfaces to produce an exclusionary effect and favor their interaction with the column. Protein hydration is generally proportional to protein size and solubility. Among proteins of similar size, this predicts that retention will increase with protein solubility. Among proteins of similar solubility, retention increases with protein size.16... 

Barlow, DJ. and P.L. Poole. 1987. The hydration of protein secondary structures. FEBS Lett 213 423 427. 

Rosenberg, A. and Somogyi, B. (1986) Conformational fluctuations, thermal stability and hydration of proteins, studies by hydrogen exchange kinetics. n Dynamic of Biochemical systems, edited by S. Damjanovich, T.Keleti and L.Tron, pp. 101-112. Amsterdam Elsevier. 

The density of bulk milk (4% fat and 8.95% solids-not-fat) at 20°C is approximately 1030 kg m 3 and its specific gravity is 1.0321. Milk fat has a density of about 902 kg m " 3 at 40°C. The density of a given milk sample is influenced by its storage history since it is somewhat dependent on the liquid to solid fat ratio and the degree of hydration of proteins. To minimize effects of thermal history on its density, milk is usually prewarmed to 40-45°C to liquify the milk fat and then cooled to the assay temperature (often 20°C). 

Belton, P.S. (2000) Nuclear magnetic resonance studies of the hydration of proteins and DNA. Cell. Mol. Life Sci. 57, 993-998. 

Just as an increase in solids-not-fat increases milk density, so does the removal of water by processing. If there were no changes in physical state or chemical activity coefficients (e.g., hydration of proteins or insolubilization of salts), the density of the concentrated milk could be calculated from an equation derived by Jenness (1962) and presented in the second edition of this book. Data presented by Mojonnier and Troy (1922) conform to the equation but lack sufficient precision to indicate the small changes associated with some of the changes in physical state. 

Figure 13 Desorption and hydration of protein bound to fat globules of ice cream mix during ageing at 5°C.

Table 23.4. Hydration of protein main-chain and side-chain functional groups. The sample consists of the 15 proteins in Table 19.1 where water molecules were located in the X-ray analysis ([596] in abbreviated form)...

Kuntz ID, Kauzmann W (1974) Hydration of proteins and polypeptides. Adv Protein Chem 28 239- 345... 

Preparation of the ice cream mix, including homogenization, pasteurization and ripening at about 4°C to allow full hydration of proteins and hydrocolloids present in the mix. 

The attention of the reader is drawn to several books and reviews on protein hydration, in addition to the reviews by Kuntz and Kauzmann (1974) and by Edsall and McKenzie (1983). Recent volumes of Methods in Enzymology (Hirs and Timasheff, 1985 Packer, 1986) describe measurements on the hydration of protein and membrane systems. Saenger (1987) has reviewed aspects of macromolecule hydration. Edsall (1980) has given a brief history of research on water. Several summaries of current research in biophysics describe work related to the hydration of macromolecules (dementi and Chin, 1986 Ehrenberg et al., 1987 Moras et al., 1987 Welch, 1986). For comprehensive treatments of the properties of water and aqueous solutions, see the multivolume treatise by Franks (e.g., Franks, 1979), the review by Edsall and McKenzie (1978), and the volume by Eisenberg and Kauzmann (1969). 

Atomic and group additivity schemes, derived from solvent accessibility calculations and measurements on model systems, have been used to estimate the thermodynamics of hydration of proteins and peptides (Eisenberg and McLachlan, 1986 Ooi and Oobatake, 1988a Ooi et al., 1987). 

Rodier, F., Bahadur, R.P., Chakrabarti, P. and Janin, J. (2005) Hydration of protein-protein interfaces. Proteins 60, 36-45. 

Rodier E, Bahadur RP, Chakrabarti P, Janin J. Hydration of protein-protein interfaces. Proteins Struct. Eunc. Genet. 2005 60 36-45. 

The formation of spanning H-bonded water networks on the surface of biomolecules has been connected with the widely accepted view that a certain amount of hydration water is necessary for the dynamics and function of proteins. Its percolative nature had been suggested first by Careri et al. (59) on the basis of proton conductivity measurements on lysozyme this hypothesis was later supported by extensive computer simulations on the hydration of proteins like lysozyme and SNase, elastine like peptides, and DNA fragments (53). The extremely interesting... 

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