Protein salts

Further efficient fermentative methods for manufacture of riboflavin have been patented one is culturing C. famata by restricting the carbon source uptake rate, thereby restricting growth in a linear manner by restriction of a micronutrient. By this method, productivity was increased to >0.17 g riboflavin/L/h (63). The other method, using Bacillus subtilis AJ 12644 low in guanosine monophosphate hydrolase activity, yielded cmde riboflavin 0.9 g/ L/3 days, when cultured in a medium including soy protein, salts, and amino acids (64). 

The main disadvantage of precipitation with a polar (water-soluble) solvent is the need for a costly distillation stage to recover the relatively laige volumes of solvent used. Another disadvantage is the precipitation of proteins, salts and, in some cases, pigments which reduces the purity and leads to discoloration of the product. To overcome these problems, precipitation using less polar solvents, such as methylethylketone, has been proposed. Only 23% (w/v) methylethylketone is sufficient to saturate the aqueous phase and precipitate exopolysaccharides quantitatively. 

Biological matrices are very complex apart from the analytes, they usually contain proteins, salts, aeids, bases, and various organie eompounds. Therefore, effeetive sample preparation must inelude partieulate eleanup to provide the component of interest in a solution, free from interfering matrix elements, and in an appropriate concentration. 

Lee K, Fitch CA, Lecomte JT, Garcfa-Moreno EB (2002) Electrostatic effects in highly charged proteins Salt sensitivity of pKa values of histidines in staphylococcal nuclease. Biochemistry 41 5656-5667. 

Matrix Water Proteins Salts Other Components... 

Calculation of Brine Components. In order to satisfy U.S.D.A. regulations, care must be taken during brine preparation so that finished product protein meets or exceeds 17 percent. The following formula can be used to determine brine composition (Isolated soy protein, salt, dextrose, polyphosphate, etc.) (6). 

The studies of Pauli he. cit.) and his co-workers, however, have revealed the fact that isohydric solutions of different acids do not effect equal combination with the isoelectric protein relatively more acetic acid for example being combined than hydrochloric acid in isohydric solutions. Again, both the actual position of these maxima as well as the magnitudes of the viscosities observed vary much with the nature of the acid employed. Thus the relatively weak oxalic acid appears to be a much stronger acid than sulphuric acid, whilst trichloracetic acid does not differ appreciably from acetic acid in its effect on the viscosity of albumin. It is probable that the degree of solvation of the protein molecules and of the protein salts must not be regarded as constant but that they vary both with the nature of the salt and in the presence of neutral salts which exert like alcohol a desolvating action more or less complete on the solvated isoelectric protein as well as on the undissociated protein salts. 

Milk consists of water, lipids, carbohydrates, proteins, salts, and a long list of miscellaneous constituents. It may contain as many as 105 different kinds of molecules. Refinement of qualitative and quantitative techniques continues to add new molecular species to the list. The constituents fall into four categories ... 

Before selecting a method to measure a specific aspect of protein functionality, one must decide on the complexity of the testing matrix. Researchers have used a single purified protein, a crude extract of proteins, a prototype food product, or an actual product to study protein functionality. For meat studies, formulated meat systems, ground muscle, myofibrillar proteins, salt-soluble proteins, actomyosin,... 

J. Laitinen, J. Samarut and E. Holtta, A nontoxic and versatile protein salting out method for isolation of DNA, Biotechniques, 17 (1994) 316-322. 

C. J. Coen, J. M. Prausnitz and H. W. Blanch, Protein salting-out phase equilibria in two-protein systems, Biotechnol. Bioeng. 1997, 53, 567-574. 

It was seen that the two readily diffusible substances, glucose and urea, did not dialyze at equivalent rates and that protein binding of calcium had to be overcome to obtain a dialysis rate proportional to its concentration. The instrument usually provides a dialysis rate (and therefore an amount dialyzed) which is proportional to the concentration of the substance being tested. However, this proportionality would need to be checked for any test adapted to automatic analysis. It was also seen that dialysis was influenced by the presence of protein, salts, membrane charges, etc., in that dialysis rate from standards was not always identical with that from plasma or serum. To date these differences have been corrected for by a constant factor. 

Remove unbound proteins, salts, and other contaminants... 

F. Thermodynamics of Protein—Salt—Water Interactions and Structural... 

In a related connection, the solubility of a protein may be considerably greater in a slightly acidified or alkalized weakly protic solvent than in the pure liquid. This would be analogous to the situation which one obtains in aqueous media, in which proteins are generally increasingly soluble the further the pH is from the isoelectric point of the protein, within certain pH limits (Cohn and Edsall, 1943, p. 606). This is probably the reason that 2-chloroethanol is such an excellent solvent for proteins (Doty, 1959). This solvent is not a very stable one, and significant amounts of HCl can be present in it. This may also account for the observation that, although bovine serum albumin is insoluble in pure acetone, methanol, and ethanol, it dissolves in them when trichloroacetic acid (1%) is added (Levine, 1954). On the other hand, the trichloroacetate counterion may itself influence the solubility of the protein salt in the nonaqueous solvents. 

The charge carried by a protein in a solution of a given pH may be regarded as approximately proportional to the number of equivalents of acid or alkali required to bring the protein system from the isoelectric point to its actual pH value. This statement presupposes, among other matters, that the electrolytes in the solution do not affect the charge of the particles, as will be the case if univalent ions only are present that the protein salts are completely ionized or ionized to a constant extent ... 

Shimizu S, McLaren WM, Matubayasi N. The Hofmeister series and protein-salt interactions. J. Chem. Phys. 2006 124 234905. 

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