Of proteins substitution

To find the quantity of protein, substitute the measured absorbance into Equation A ... 

The schematic structure of heme is shown in Figure 2. Porphyrin acts as a ligand of Fe(II) or Fe(III). It is the variations in the type of protein substitutes or the method of securing coordination between heme and the protein portion that are the source of the above-listed functional diversity of heme-containing proteins. 

MacDoneild A, Rylance G, Davies P, Asplin D, HaU SK, Booth IW. Administration of protein substitute and quality of control in phenylketonuria a randomized study. J Inherit Metab Dis. 2003 26(4) 319-26. 

Prospective longitudinal study No correlation with eneigy intake and plasma Phe level Distribution of protein substitute affects 24 h Phe variability Excess of several amino acid for some patients when fed protein at these levels... 

Randomized crossover study Poorer Phe control seen with lower amount of protein substitute Retrospective study. Height growth not clearly related to protein intake. Natural protein rather than total protein correlated with head circumference... 

C4H6N2O2. Sublimes 260"C sparingly soluble in water hydrolysed by alkalis or mineral acids to glycylglycine. It and substituted dike-topiperazines are formed by the condensation of amino-acids, and are obtained in small quantities on the hydrolysis of proteins. 

This method has been successfully applied to the substituted indole 2.6B, an analogue of the teleocidin type of protein kinase activators[ll]. 

While electrospray is used for molecules of all molecular masses, it has had an especially marked impact on the measurement of accurate molecular mass for proteins. Traditionally, direct measurement of molecular mass on proteins has been difficult, with the obtained values accurate to only tens or even hundreds of Daltons. The advent of electrospray means that molecular masses of 20,000 Da and more can be measured with unprecedented accuracy (Figure 40.6). This level of accuracy means that it is also possible to identify post-translational modifications of proteins (e.g., glycosylation, acetylation, methylation, hydroxylation, etc.) and to detect mass changes associated with substitution or deletion of a single amino acid. 

Vegetable proteins other than that from soy have potential appHcability in food products. Functional characteristics of vegetable protein products are important factors in determining their uses in food products. Concentrates or isolates of proteins from cotton (qv) seed (116), peanuts (117), rape seed (canola) (118,119), sunflower (120), safflower (121), oats (122), lupin (123), okra (124), and com germ (125,126) have been evaluated for functional characteristics, and for utility in protein components of baked products (127), meat products (128), and milk-type beverages (129) (see Dairy substitutes). 

Although FeMo-cofactor is clearly knpHcated in substrate reduction cataly2ed by the Mo-nitrogenase, efforts to reduce substrates using the isolated FeMo-cofactor have been mosdy equivocal. Thus the FeMo-cofactor s polypeptide environment must play a critical role in substrate binding and reduction. Also, the different spectroscopic features of protein-bound vs isolated FeMo-cofactor clearly indicate a role for the polypeptide in electronically fine-tuning the substrate-reduction site. Site-directed amino acid substitution studies have been used to probe the possible effects of FeMo-cofactor s polypeptide environment on substrate reduction (163—169). Catalytic and spectroscopic consequences of such substitutions should provide information concerning the specific functions of individual amino acids located within the FeMo-cofactor environment (95,122,149). 

Free substitution of protein meals ia feeds is much more restricted than interchange of oils ia foods. Because of a good balance of essential amino acids, soybean meal is an indispensable ingredient for efficient feeding of nonmminants, eg, poultry and swine. Soybeans provide ca 60% of the world s protein meals, including fish meal (Table 14). Of the 30.0 x 10 t of soybean meal produced in the United States in 1994—1995, 24.2 x 10 t was used domestically, primarily in feeds, and 5.7 x 10 t was exported (50). In the United States, poultry consume the largest share of soybean meal, followed by swine. Lesser amounts are fed to beef and dairy catde. Soybean meal is a principal ingredient in many pet foods (see Feeds and feed additives). 

Grain that is usable as food or feed is an expensive substrate for this fermentation process. A cheaper substrate might be some source of cellulose such as wood or agricultural waste. This, however, requires hydrolysis of cellulose to yield glucose. Such a process was used in Germany during World War II to produce yeast as a protein substitute. Another process for the hydrolysis of wood, developed by the U.S. Forest Products Laboratory, Madison, Wisconsin, uses mineral acid as a catalyst. This hydrolysis industry is very large in the former Soviet Union but it is not commercial elsewhere. 

There are no universally accepted definitions of substitute dairy foods, which are referred to as imitations, simulates, substitutes, analogues, and mimics and are associated with terms such as filled, nondairy, vegetable nondairy, and artificial milk, cheese, etc. The term nondairy has been used indiscriminately to describe both imitation dairy products and products legally defined as not being imitation dairy products. Dairy substitutes can be divided into three types those in which an animal or vegetable fat has been substituted for milk fat those that contain a milk component, eg, casein [9000-71-9] or whey protein and those that contain no milk components (see Milk and milkproducts). The first two types make up most of the substitute dairy products. 

Phosphates, which react with calcium to reduce the calcium ion activity, assist in stabilizing calcium-sensitive proteins, eg caseinate and soy proteinate, during processing. Phosphates also react with milk proteins. The extent of the reaction depends upon chain length. Casein precipitates upon addition of pyrophosphates, whereas whey proteins do not. Longer-chain polyphosphates cause the precipitation of both casein and whey proteins. These reactions are complex and not fully understood. Functions of phosphates in different types of dairy substitutes are summarized in Table 9 (see also Food additives). 

The composition of dairy substitutes is highly variable and generally represents the least-cost formulation consistent with consumer acceptance of the product. These imitations invariably have lower fat and protein levels than the dairy products that they are made to resemble. The gross compositions of filled milk, meUorine, synthetic milk, sour cream, coffee whiteners, whipped toppings, and cheese are Hsted in Table 10. A comparison of the composition of certain dairy products and their substitutes is presented in Table 11. 

PA.G. Statement of Milk Substitutes, No. 6, Protein Advisory Group of the United Nations System, New York, 1970. 

CM Topham, A McLeod, E Eisenmenger, JP Overmgton, MS Johnson, TL Blundell. Erag-ment ranking in modelling of protein structure. Conformationally constrained environmental ammo acid substitution tables. J Mol Biol 229 194-220, 1993. 

One of the historically most significant examples of aromatie nueleophilie substitution is the reaetion of amines with 2,4-dinitrofluorobenzene. This reaetion was used by Sanger to develop a method for identifieation of the N-terminal amino acid in proteins and the proeess opened the way for struetural eharacterization of proteins and other biopolymers. 

Pentafluorobenzyl bromide has been used in the derivatization of mercaptans [55] and phenols [36], m the analysis of prostaglandins [37], and in quantitative GC-MS [5S] 1,3 Dichlorotetrafluoroacetone is used for the derivatization of amino acids to the corresponding cyclic oxazolidinones and allows the rapid analysis of all 20 protein ammo acids [d] Pentafluorophenyldialkylchlorosilane derivatives have facilitated the gas chromatographic analysis of a wide range of functionally substituted organic compounds, including steroids, alcohols, phenols, amines, carboxylic acids, and chlorohydrms [4]... 

Nucleophilic aromatic substitution is much less common than electrophilic substitution but nevertheless does have certain uses. One such use is the reaction of proteins with 2,4-dinitrofluorobenzene, known as Sanger s reagent, to attach a "label" to the terminal NH2 group of the amino acid at one end of the protein chain. 

Dextran can be produced in a range of molecular weights and crossed-linked or substituted with a variety of functional groups. These products (Sephadex) are routinely used in the purification of proteins and pharmaceutical and other medically important compounds. 

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