Dehydrated protein

Ross and Billing, by means of refractive index measurements on spores and vegetative cells of B. cereus, B. cereus var. mycoides, and B. megaterium, found the values to be very high and comparable with that of dehydrated protein. This suggested that they contained much less water than the vegetative cells. 

Griebenow, K. and Barletta, G., Dehydrated protein powders as hiocatalysts in nonaqueous solvents. In Lyophilization of Biopharmaceuticals (Biotechnology Pharmaceutical Aspects), Costantino, H.R. and Pikal, M.J. (eds). AAPS Press Arhngton, VA, 2004, pp. 643-668. 

Organic solvents also decrease protein solubility, but they are not as widely used as ammonium sulfate. They are thought to function as precipitating agents in two ways (1) by dehydrating proteins, much as ammonium sulfate does, and (2) by decreasing the dielectric constant of the solution. The organic solvents used (which, of course, must be miscible with water) include methanol, ethanol, and acetone. 

Hydrates have further applications in bioengineering through the research of John and coworkers (Rao et al., 1990 Nguyen, 1991 Nguyen et al., 1991, 1993 Phillips et al., 1991). These workers have used hydrates in reversed micelles (water-in-oil emulsions) to dehydrate protein solutions for recovery and for optimization of enzyme activity, at nondestructive and low-energy conditions. 

Bulgin s data show loss of DTA peaks at 114° and 135°C if SC is heated for 2 hrs at 100°C or extracted with chloroform methanol (2 1) (103). Rehydration restores the 114°C peak of the heated SC, but the 135°C peak is irreversibly lost. The reverse is true for extracted SC rehydration restores the 135 °C peak but not the 114 °C peak. These results suggest association of the 114°C peak with water in lipid-rich hygroscopic substance heating would drive oflF the water without destroying the lipids. However, the lipids would be removed by the chloroform methanol. The 135 °C peak may be associated with water bound by protein surfaces which resist chloroform-.methanol yet are denatured by heat. Perhaps dehydrated protein surfaces become bonded together thereby eliminating hydrophilic sites. 

The practical solution to the protein stability dilemma is to remove the water. Lyophilization (freeze-drying) is most commonly used to prepare dehydrated proteins, which, theoretically, should have the desired long-term stability at ambient temperatures. However, as will be described in this review, recent infrared spectroscopic studies have documented that the acute freezing and dehydration stresses of lyophilization can induce protein unfolding [8-11]. Unfolding not only can lead to irreversible protein denaturation, even if the sample is rehydrated immediately, but can also reduce storage stability in the dried solid [12,13]. 

To characterise the functionally Important motions in hydrated myoglobin, simulations on its hydrated CO complex have been performed by Steinbach and Brooks [35], In this study the temperature and hydration dependence of equilibrium dynamics was investigated. The authors performed two sets of MD simulations, torsionally restrained and unrestrained calculations on dehydrated carbonmonoxy myoglobin at different temperatures between 100 K and 400 K were compared to that on the hydrated protein. They found that the dehydrated protein exhibits almost exclusively harmonic fluctuations at all temperatures, while remarkable anharmonic motions have been detected in the hydrated protein at about 200 K independently whether the torsions were constrained. The... 

Polymers such as poly(ethyleneglycol) also serve to dehydrate proteins in solution as do salts, and they alter somewhat the dielectric properties in a manner similar to organic... 

A potential source of red and brown heme pigments is animal blood and its dehydrated protein extracts, which mainly consist of hemoglobin and may be used as red and brown colorings to meat products. However, in most countries their usage as a food coloring agent is not permitted. 

PEI is a well-established technique for tumor ablation (Bartolozzi and Lencioni 1996). It induces tumor necrosis as a result of cellular dehydration, protein denaturation, and chemical occlusion of tumor vessels. It is best administered by using ultrasound guidance because ultrasound allows for continuous real-time monitoring of the injection. This is crucial to realize the pattern of tumor perfusion and to avoid excessive ethanol leakage outside the lesion. Fine noncutting needles, with either a single end hole or multiple side holes, are commonly... 

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