Protein isolate, definition

Solubility. The results from the solubility experiments are given in Figures 4 and 5. The broken curve is the solubility curve for the original soy protein isolate (Purina 500 E) the nitrogen solubility of this product at neutral pH is below 40%, which indicates that the isolate has been partly denatured during its processing. The sample denoted as DH = 1.0% is the control and it is clearly demonstrated that the acid treatment has caused further aggregation and denaturation. The definitely positive DH-value... 

The first soybean protein ingredients made commercially available for food use included full-fat and defatted soy flours and grits (3, 7, 8). These products contain ca. 46-59% protein (NX 6.25) on a moisture-free basis and are available with various heat treatments for specific end-use. Soy protein concentrates and soy protein isolates were introduced into the market about 15 years ago (3, 9, 10, II). By definition soy protein concentrates must contain no less than 70% protein (N X 6.25) and isolates no less than 90% protein (N X 6.25), all on a moisure-free basis. In the past several years there has been much activity in the commercialization of textured soy protein products intended for the extension and replacement of meat. These textured products may be obtained through fiber spinning, shred formation, extrusion, or compaction (12, 13, 14, 15). In addition, soybean milk solids and the heterogeneous proteins in soybean whey might serve as useful substrates in chemical modifications for food use. This short recitation of commercial products illustrates the type of crude protein fractions available for practical modification. Many useful functional properties have been ascribed to these new food proteins. 

In summary, it appears that the adsorption of proteins at fluid/fluid interfaces is very complex and involves several steps that are not encountered in classical surfactants or even polymeric surfactants. All the parameters that are controlling the surface activity may be changed by chemical or physicochemical modifications, such as covalent attachment of various groups, breaking of disulfide bonds, de-naturation by heat, etc. It is important to note that while changing one parameter, one may change the others as well, and therefore it would be difficult to isolate definite parameters. 

With the establishment of techniques for isolation and characterization of lipoprotein proteins, further definition of the lipoprotein changes in biliary obstruction ought to be possible. Furman et al. (1961) have exposed in vitro sera from subjects with biliary obstruction to sonic forces. Cholesterol and phospholipid contents of the LDL class diminished while a comparable increase of these lipids in the HDL class occurred. These data were interpreted to indicate that in obstructive jaundice serum LDL and HDL are to a certain extent associated. 

Definition Globular protein isolated from milk Uses Antistat in cosmetics... 

Definition Protein isolated by the silk worm, Bombyx mori... 

Lipids are naturally occurring organic molecules that have limited solubility in water and can be isolated from organisms by extraction with nonpolar organic solvents. Fats, oils, waxes, many vitamins and hormones, and most nonprotein cell-meznbrane components are examples. Note that this definition differs from the sort used for carbohydrates and proteins in that lipids are defined by a physical property (solubility) rather than by structure. Of the many kinds of lipids, we ll be concerned in this chapter only with a few triacvlglycerols, eicosanoids, terpenoids, and steroids. 

Water soluble protein with a relative molecular mass of ca. 32600, which particularly contains copper and zinc bound like chelate (ca. 4 gram atoms) and has superoxide-dismutase-activity. It is isolated from bovine liver or from hemolyzed, plasma free erythrocytes obtained from bovine blood. Purification by manyfold fractionated precipitation and solvolyse methods and definitive separation of the residual foreign proteins by denaturizing heating of the orgotein concentrate in buffer solution to ca. 65-70 C and gel filtration and/or dialysis. 

Definition of Ej and E2 eonformations of the a subunit of Na,K-ATPase involves identification of cleavage points in the protein as well as association of cleavage with different rates of inactivation of Na,K-ATPase and K-phosphatase activities [104,105]. In the Ei form of Na,K-ATPase the cleavage patterns of the two serine proteases are clearly distinct. Chymotrypsin cleaves at Leu (C3), Fig. 3A, and both Na,K-ATPase and K-phosphatase are inactivated in a monoexponential pattern [33,106]. Trypsin cleaves the E form rapidly at Lys ° (T2) and more slowly at Arg (T3) to produce the characteristie biphasic pattern of inactivation. Localization of these splits was determined by sequencing N-termini of fragments after isolation on high resolution gel filtration columns [107]. 

Several other cell types have also been shown to secrete histamine-releasing activity, some of which may be peptide in nature (although more work is necessary for a definitive characterization). For example, human lung macrophages cultured for 24 h have been shown to release a soluble factor (12 and 30 kDa) that stimulates isolated human lung mast cells and human basophils to release histamine [ 145]. The generation and release of this factor developed over time (> 1 h) and was blocked by cycloheximide, indicating that protein... 

Lipids are naturally occurring organic molecules, isolated from animal or plant cells by extraction with nonpolar organic solvents. This definition defines lipids in terms of a physical property (solubility) and differs from structural definitions used for proteins or carbohydrates. Not surprisingly, lipids are highly varied in their structure from the medicinal chemistry perspective, there are five classes of lipids ... 

The proteins of milk are of great importance in human nutrition and influence the behavior and properties of the dairy products containing them. They have been studied more extensively than any other proteins except possibly those of blood. Since milk contains a number of different proteins, they must be fractionated and the proteins of interest isolated before definitive work can be done on their composition, structure, and chemical and physical properties. 

The chemical nature of enzyme was controversial for a long time, until Buchner succeeded in isolating an enzyme system (zymase) from yeast in a cell-free extract in 1897.2) Urease was then crystallized by Sumner in 1926,3) followed by crystallization of several proteolytic enzymes by Northlop and his colleagues. At present the chemical nature of enzyme is defined as a protein with catalytic activity based on the specific activaiton of its substrate. However, this definition has been somewhat open to debate since a catalytic RNA, ribozyme, was discoved in 1982. 

From a strict biochemical point of view a clear-cut definition of the role of the liver in the biosynthesis of any particular plasma protein can be made only when the particular protein has been clearly and cleanly isolated, as in the case of fibrinogen. The practical difficulties of effecting such isolations on a small scale from isotopic labeling studies of the plasma proteins, such as we have described, seriously militate against such a detailed demonstration at present. The use of fractionation techniques with greater resolving power such as acrylamide gel electrophoresis already show some promise in our laboratory toward affording a more definitive picture of the biosynthetic role of the liver and the nonhepatic tissues in plasma protein production. 

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