Dilute salt solution

Globulins. Proteins insoluble in water, soluble in dilute salt solutions. They include such proteins as myosin from muscle, fibrinogen from blood and edcstin from hemp. 

Enzymes are proteins of high molecular weight, several of which have been isolated in a pure State consequently their precise nature is in some instances still obscure. They form solutions in water and in dilute salt solutions, and are precipitated when such solutions are saturated with ammonium sulphate. 

Breslow studied the dimerisation of cyclopentadiene and the reaction between substituted maleimides and 9-(hydroxymethyl)anthracene in alcohol-water mixtures. He successfully correlated the rate constant with the solubility of the starting materials for each Diels-Alder reaction. From these relations he estimated the change in solvent accessible surface between initial state and activated complex " . Again, Breslow completely neglects hydrogen bonding interactions, but since he only studied alcohol-water mixtures, the enforced hydrophobic interactions will dominate the behaviour. Recently, also Diels-Alder reactions in dilute salt solutions in aqueous ethanol have been studied and minor rate increases have been observed Lubineau has demonstrated that addition of sugars can induce an extra acceleration of the aqueous Diels-Alder reaction . Also the effect of surfactants on Diels-Alder reactions has been studied. This topic will be extensively reviewed in Chapter 4. 

Recovery. The principal purpose of recovery is to remove nonproteinaceous material from the enzyme preparation. Enzyme yields vary, sometimes exceeding 75%. Most industrial enzymes are secreted by a microorganism, and the first recovery step is often the removal of whole cells and other particulate matter (19) by centrifugation (20) or filtration (21). In the case of ceU-bound enzymes, the harvested cells can be used as is or dismpted by physical (eg, bead mills, high pressure homogenizer) and/or chemical (eg, solvent, detergent, lysozyme [9001 -63-2] or other lytic enzyme) techniques (22). Enzymes can be extracted from dismpted microbial cells, and ground animal (trypsin) or plant (papain) material by dilute salt solutions or aqueous two-phase systems (23). 

Nylon 66 is produced by the reaction of hexamethylenediamine and adipic acid (see Chapters 9 and 10 for the production of the two monomers). This produces hexamethylenediammonium adipate salt. The product is a dilute salt solution concentrated to approximately 60% and charged with acetic acid to a reactor where water is continuously removed. The presence of a small amount of acetic acid limits the degree of polymerization to the desired level ... 

Pai, C.K., and Smith, M.B. (1995) Rate enhancement in dilute salt solutions of aqueous ethanol the Diels-Alder reaction.. Org. Chem. 60, 3731-3735. 

A variation on simple extraction is extraction with a dilute salt solution. In this case, either a dilute solution of calcium or potassium chloride is commonly used. The concept is that these dilute solutions mimic the root environment to some extent. In addition to extraction, these solutions are often used in the determination of soil pH [6], A typical dilute salt solution extraction of soil is given in Procedure 11.3 ... 

Cytochrome c can easily be extracted from tissue particles by dilute salt solutions. It was isolated by Keilin and Hartree in 1930 and shown to contain a porphyrin ring structure. In 1933 Zeilen and Reuter established that cytochrome c was a heme (iron-porphyrin) protein. Slightly different forms of cytochrome a were distinguished in yeast and bacteria by Keilin in 1934 and the different properties of cytochrome a and a3 by Tamiya et al. in 1937. The identity of cytochrome 03, the enzyme which activates oxygen with Warburg s atmungsferment, was proposed by Keilin in 1939. Cytochrome a/a3 was renamed cytochrome oxidase by Malcolm Dixon (1939). The oxidation route then offered was ... 

Lynen had studied chemistry in Munich under Wieland his skill as a chemist led to the successful synthesis of a number of fatty acyl CoA derivatives which proved to be substrates in the catabolic pathway. Many of these C=0 or C=C compounds had characteristic UV absorption spectra so that enzyme reactions utilizing them could be followed spectrophotometrically. This technique was also used to identify and monitor the flavoprotein and pyridine nucleotide-dependent steps. Independent evidence for the pathway was provided by Barker, Stadtman and their colleagues using Clostridium kluyveri. Once the outline of the degradation had been proposed the individual steps of the reactions were analyzed very rapidly by Lynen, Green, and Ochoa s groups using in the main acetone-dried powders from mitochondria, which, when extracted with dilute salt solutions, contained all the enzymes of the fatty acid oxidation system. 

Protein subunits will partially dissociate from crystalline ferritin in dilute salt solutions to yield a non-crystallizable ferritin. The non-crystallizable ferritin, in turn, in the presence of apoferritin appears to pick up protein subunits and by action yield crystalline ferritin molecules. The scheme for this process is shown in Fig. 6. The salient feature of this scheme is the initial formation of an iron micelle from soluble iron chelates which is then stabilized by protein subimits S5uithesized by the tissue (726). Harrison and Gregory 127) have used glacial acetic acid to dissociate apoferritin completely. When the pH is adjusted to 4 in the presence of thiol compoimds, apoferritin is rapidly formed, indicating strong subunit interaction. 

Viscosity data for fairly dilute salt solutions are usually discussed in terms of the Jones-Dole equation (3)... 

Early work was done with a sized fraction (about 0.1 mm) obtained by grinding zeolite pellets which contained a significant amount of binder. Subsequently, the pure zeolite powder was used. In all cases the zeolite was washed with a large volume of dilute salt solution, sometimes containing a small amount of acetate buffer at about pH 5.5, and precautions were taken to avoid hydrolytic precipitation of the metals. 

Product Elution. Several salt solutions, including LiCl, Na2S04, NH4NO3, and Ca(N03)2, have been used as eluents. In some cases a low concentration of formate or acetate was added to buffer the solution at pH 5-5.5. All the solutions were about equally effective as long as the concentration was >2-4M for the monovalent cations and 0.5M for the Ca-(N03)2 at lower concentrations the fraction eluted decreased. Concentrated LiCl was used initially because it was a suitable medium for subsequent processing of the product, but more dilute salt solutions are less viscous and more convenient to work with. 

ALBUMIN. An albumin is a member of a class of proteins which is widely distributed in animal and vegetable tissues. Albumins are soluble in water and in dilute salt solutions, and are coagulable by heat. 

Albumins and globulins 12-20 Extractable by water of dilute salt solutions (e.g., 0.1-0.5 M NaCl) Contains enzymes (amylases, proteinases, lipoxygenases) Rich in Lys, Asp, Ala, Cys, Leu, and Arg low in Met content... 

A peculiar method of desalting water is the osmionic demineralization developed by G. W. Murphy (702,103). In a multicell are circulated side by side a very concentrated salt solution, a moderately concentrated salt solution and a dilute salt solution to be desalted. The arrangement is now such that only Na+ and Cl- ions can move from the brine to the moderately concentrated salt solution, when simultaneously also Na+ and Cl- ions can move from the dilute salt solution to this moderately concentrated solution. In this manner the dilute solution is desalted. 

Figure 5.5 Water permeability as a function of sodium chloride permeability for membranes made from cellulose acetate of various degrees of acetylation. The expected rejection coefficients for these membranes, calculated for dilute salt solutions using Equation (5.6),...

The concentration of a co ion in an ion-exchange membrane can be calculated from the Donnan equilibrium. For a monovalent salt and a dilute salt solution and assuming the activity coefficients of the salt in the membrane and the solution to be 1, the co ion concentration in the membrane is given to a first approximation by... 

An alternative method for reducing excess salts was described by Chen etal. (20), wherein the sample was placed in a dialysis tube then dialyzed against a degassed, dilute salt solution. This method and apparatus are effective when large amounts of reduced sample are required ... 

This envelope is a syncytial layer involving two cells Ailing the space between the embryo and the egg shell it is responsible for the formation of the embryophore and oncospheral membrane (204). After the latter is formed, what is left of the inner envelope becomes the cytoplasmic and gelatinous layers-zones I and II, respectively, in H. diminuta (Fig. 7.14). The latter has the ability to swell readily in dilute salt solutions, a property which may facilitate the escape of the oncosphere during hatching (p. 191) (442). 

Quantitative theories of salt solutions are well established. In dilute salt solutions, ion-ion interactions can be described to a first approximation, in terms of charge-charge interactions. These long-range interactions produce a stabilizing influence, the chemical potential of the salt in solution being less than in the corresponding... 

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