Fully hydrated protein

The thermodynamic properties of the hydradon shell (Table VIII) show it to be slightly, but not strongly, different from the bulk water. The free-energy difference is only 0.5 kcal/mol of water, slighdy less than the ambient thermal energy. The heat capacity, enthalpy, and volume changes associated with hydration are 10—15% of the bulk water values. 

About 300 water molecules are sufficient to cover the lysozyme surface. This is a remarkably small amount of water. Calculations based on the crystal structure of lysozyme show that the surface is about 6000 A in area (Lee and Richards, 1971 Shrake and Rupley, 1973). Thus, each water covers, on average, about 20 A, which is twice the projection of a water molecule packed as in the liquid. Since 20 is the most area a water molecule can cover and maintain hydrogen bonding, there can be no multilayer water. Moreover, whatever arrangements there are at the surface must integrate simply into the bulk water namely, there is no B shell of disordered water, required to interface the water adjacent to the protein surface with the bulk solvent. 

Thermodynamic variable Difference (hydrated protein — pure components) 

The crystallographic results of Blake et al. (1983), who analyzed high-resolution X-ray diffraction data for human lysozyme (HL) and tortoise egg white lysozyme (TEWL) fit the above picture. The crystallographic 

Measurements of the dynamic properties of the surface water, particularly NMR measurements, have shown that the characteristic time of the water motion is slower than the bulk water value by a factor of less than 100. The motion is anisotropic. There is litde or no irrotadonally bound water. Study of a protein labeled covalently with a nitroxide spin probe (Polnaszek and Bryant, 1984a,b) has shown that the diffusion constant of the surface water is about 5-fold below the bulk water value. The NMR results are in agreement with measurements of dielectric relaxation of water in protein powders (Harvey and Hoekstra, 1972). 

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Calorimetric data have shown that only half of the total water sorbed by elastin (about 0.6 g water / g dry protein) is really "bound", the remaining water being freezable ( 1). The volumetric data reported in the literature (15,16) refer therefore to an essentially heterophase system, so that the negative and very large coefficient of thermal expansion of the fully hydrated protein does not appear to be suitable for the Interpretation of the thermoelastic data and calculation of the... 

The 15N spectral peaks of fully hydrated [15N]Gly-bR, obtained via cross-polarization, are suppressed at 293 K due to interference with the proton decoupling frequency, and also because of short values of T2 in the loops.208 The motion of the TM a-helices in bR is strongly affected by the freezing of excess water at low temperatures. It is shown that motions in the 10-j-is correlation regime may be functionally important for the photocycle of bR, and protein-lipid interactions are motionally coupled in this dynamic regime. 

The mix is then homogenized at 105 to 210 kg/cm2 (1500 to 3000 lb/in2) to subdivide milk fat globules to sizes ranging from 0.5 to 2 m in diameter. This process is essential to produce a mix with adequate aeration properties so that the final product will contain < 175- m-diameter air cells to contribute a smooth texture. The homogenized mix is cooled and aged to fully hydrate the hydrocolloids, e.g., milk proteins, stabilizers and corn sweetners, and to provide adequate viscosity to the mix. 

The outermost layer of the skin, the cornified layer or stratum corneum, has been identified as the principal diffusion barrier for substances, including water [2,3]. It is approximately 10 to 20 pm thick when dry but swells to several times this thickness when fully hydrated [17], It contains 10 to 25 layers lying parallel to the skin surface of nonviable cells, the corneocytes, which are surrounded by a cell envelope and imbedded in a lipid matrix. This architecture is often modeled as a wall-like structure, with the corneocytes as protein bricks embedded in a lipid mortar [18]. Similarly to the viable epidermis, desmosomes (corneodesmosomes) contribute to the cell cohesion. 

Peak maxima are observed near 2930 and 2890 cm-1. CH stretching features for fatty compounds (and proteins) and carbohydrates are significantly different. More bands are observed for crystalline simple sugars, than complex, amorphous, or fully hydrated carbohydrates. 

These products are usually made from formulations of high protein content (soya, meat particles, etc.), so the continuous phase at the die exit is proteinaceous, with inclusions of carbohydrate. These products are required to deliver a significant textural strength (bite) even when fully hydrated. Massive expansion and low bulk density is not required. Instead, a degree of fibrosity (anisotropic structure) is required to simulate meat. The early structures were extruded by processes similar to those discussed above, but with a deliberately low expansion. This was achieved by extruding with a higher moisture content and die exit temperatures below 100°C (Cheftel et al. 1992 Liu et al. 2005). 

Region 1, dilute protein solution to 0.38 h The partial specific heats are constant and the protein is fully hydrated. 

Temperature and hydration level are linked in determining the dynamics of protein and solvent. The dry protein shows, for all temperatures, only the restricted motion found below the critical temperature for hydrated samples. A fully hydrated sample shows strong temperature dependence for the dynamic properties of both protein and hydration water, for temperatures above the critical temperature. Partially hydrated samples behave complexly. Goldanskii and Krupyanskii (1989) gave a particularly good discussion of the linkage between the effects of temperature and hydration. 

The inhibition of molecular mobility at low water content was better reflected in the restrictions for protein denaturation, starch gelatinization, and water crystallization. Starch gelatinization was only observed in fully hydrated systems. The increase in water content was also reflected on the increased extent of protein denaturation and the decrease of the temperatures at which this transition occurred. Freezable water was detected in samples of... 

In conclusion, the most interesting results of the present work are first, that the volumetric temperature coefficients of elastin at low and moderate levels of hydration are positive and small (rather than negative and large, as reported for the fully hydrated but heterophase protein) and, second, that the interaction with water is accompanied, as reported previously for wool, by large volume changes, which appear to be indicative of strong interactions at the molecular level. 

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