Extraction of proteins and amino acids

Extraction of Proteins and Amino Acids Using Reversed Micelles... 

The solubilisation of proteins and amino acids in organic solvents by reversed micelles provides a new method for the selective recovery, separation and concentration of bioproducts using liquid->liquid extraction techniques. Selectivity is affected by electrostatic interactions between the charged residues or moieties of the solute and the surfactant headgroups. These interactions are mediated by electrostatic screening as affected by solution ionic strength. The more hydrophobic the amino acid residue, the more favourable is the solubilisation of this residue in the partially structured water pool of the reversed micelle relative to the bulk, unstructured water phase. 

Recent development of the use of reversed micelles (aqueous surfactant aggregates in organic solvents) to solubilize significant quantities of nonpolar materials within their polar cores can be exploited in the development of new concepts for the continuous selective concentration and recovery of heavy metal ions from dilute aqueous streams. The ability of reversed micelle solutions to extract proteins and amino acids selectively from aqueous media has been recently demonstrated the results indicate that strong electrostatic interactions are the primary basis for selectivity. The high charge-to-surface ratio of the valuable heavy metal ions suggests that they too should be extractable from dilute aqueous solutions. 

Recently however, it has been recognized that liquid extraction is a potential method in the primary recovery of fermentation cell culture products, such as proteins and amino acids. The separation problem, however, is difficult because the product mixtures are often complex, including cell debris and enzymes. Proteins are not suitable for conventional solvent extraction because of incompatibility with organic solvents, but can be handled in aqueous two-phase systems or by extraction in reverse micellar systems (Chapter 15). 

The mechanism of separation of biological molecules such as proteins and amino acids, and the parameters that affect the extraction distribution coefficient and the kinetics of extraction have been studied more extensively than the extraction of inorganic solutes. This is mainly due to the variety of size and structure of these molecules and, furthermore, to the fact that their characteristics may be adversely affected by their contact with solvents and surfactants. 

Fluorimetric methods for the determination of amino acids are generally more sensitive than colorimetric methods. Fluorescamine (4-phenyl-spiro[furan-2(3H),l -phthalan]-3,3 -dione) and o-phthaldialdehyde (OPA) substances are used for protein analysis. Fluorescamine reacts with amino groups to form fluorophores that excite at 390 nm and emit at 475 nm (Weigele et al., 1972). Applications of fluorescamine include monitoring the hydrolysis of K-casein (Beeby, 1980 Pearce, 1979) and quantification of proteins, peptides, amino acids in extracts (Creamer et al., 1985). OPA produces fluorescence on reaction with 2-mercaptoethanol and primary amines, with strong absorption at 340 nm. Lemieux et al. (1990) claimed that this method was more accurate, convenient, and simple for estimating free amino acids than the TNBS, ninhydrin, or fluorescamine methods. 

The first intimation that mutagens could be formed from natural food substances came from the laboratory of Sugimura, where it was found that mutagenic activity was found in smoke condensates or in DMSO extracts of the charred surface of fish and meat. This activity could not be accounted for by the amounts of BaP and PAH known to be present. Extracts of pyrolysates of various proteins and amino acids were also mutagenic (14). 

CAS 91081-61-7 EINECS/ELINCS 293-667-4 Definition Extract of fetal calves includes proteins and amino acids... 

Until now the most-used additives to frozen fish have been various forms of polyphosphates. These have been able to reduce drip loss, giving products containing a maximum amount of water. There is, however, a trend to reduce the application of polyphosphates in frozen fish. Other compounds, like for example polydextrose (Lanier and Akahane, 1986) or other modified polysaccharides (Sych et al., 1990) have similar effects, but the optimum situation would be to use ingredients derived from the fish itself. This could be obtained through the use of the hydrolysates mentioned. It still remains to be explained what the active components are, and what kind of profile of peptides and amino acids would be required to obtain the optimal effects. Previously a lot of work has been done in trying to manufacture fish protein hydrolysates through the combined action of enzymes and fat-extracting chemicals (Tannenbaum et al., 1974). This never became a success (Pariser et al., 1978), partly because... 

At pH = 7.0 and 37°C (310 K, blood temperature) the enthalpy and Gibbs energy of hydrolysis are A H = —20 kj moT and Afi = —31 kj moT , respectively. Under these conditions, the hydrolysis of 1 mol ATP (aq) results in the extraction of up to 31 k) of energy that can be used to do non-expansion work, such as the synthesis of proteins from amino acids, muscular contraction, and the activation of neuronal circuits in our brains, as we shall see in Chapter 5. If no attempt is made to extract any energy as work, then 20 kJ (in general, AH) of heat will be produced. 

Uses Defoamer in food processing, fennentation and extraction induding starch extraction from com flour, protein extraction from vegs., defoamer in biochemical media in the prod, of citric and amino acids, nat. flavors Features Mixes easily with water silicone-free does not affect the dissolved oxygen rale stable to conventional sterilization conditions Properties CL, colorless liq. (5% in deionized water) dens. 1.015-1.025 vise. 415 cSI (40 C) f.p. < -20 C acid no. < 3 Use Level 5040 ppm in fermentation process Environmental No toxicity towards a wide range of micro-organisms Biospumex FDA 165 K [Cognis]... 

Since the discovery of amino acids in animal and plant proteins in the nineteenth century, most amino acids have been produced by extraction from proteia hydroly2ates. However, there are many problems in the efficient isolation of the desired amino acid in the pure form. 

An alternative to the extraction of intact PHA polymer is the isolation of PHA monomers, oligomers, or various derivatives such as esters [74]. PH As are composed of stereo-chemically pure P-3-hydroxyacids, and therefore can be used as a source of optically pure organic substrates for the chemical and pharmaceutical industry [79]. In this protocol, the defatted cake containing PHA polymer would be chemically treated to obtain the PHA derivatives. For example, transesterification of the meal with methanol would give rise to methyl esters of 3-hydroxyalkanoic acids. The PHA derivatives would then be separated from the meal with appropriate solvents. One potential disadvantage of this method is the potential alteration of the quality of the residual meal if the harsh chemical treatments required for the production of PHA derivatives lead to protein or amino acid breakdown. 

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