Protein production

When the cell requires instructions for protein production, part of the code on DNA, starting at an initiator and ending at a stop codon, is converted into a more mobile form by transferring the DNA code into a matching RNA code on a messenger ribonucleic acid (mRNA), a process known as transcription. The decoding, or translation, of mRNA then takes place by special transfer ribonucleic acids (tRNA), which recognize individual codons as amino acids. The sequence of amino acids is assembled into a protein (see Proteins section). In summary, the codes on DNA... 

The three main sources of competitive advantage in the manufacture of high value protein products are first to market, high product quaUty, and low cost (3). The first company to market a new protein biopharmaceutical, and the first to gain patent protection, enjoys a substantial advantage. The second company to enter the market may find itself enjoying only one-tenth of the sales. In the absence of patent protection, product differentiation becomes very important. Differentiation reflects a product that is purer, more active, or has a greater lot-to-lot consistency. 

The reground flour is channeled to a classifier, where swirling air fuimels the larger particles down and away while the smaller fines are lifted up and separated. Repeating the process 20—30% of the flour is separated into a low protein product suitable for cakes and pastries 5—15% makes up the fine fraction, containing 15—22% protein. 

The fermentation of / -paraffins in the C q to range for protein production has provided a new oudet for these hydrocarbons (see Foods, nonconventional). Because it operates in Hquid phase, the UOP Molex process can readily accomplish the separation of / -paraffins from such a wide boiling feedstock. 

PVDF-based microporous filters are in use at wineries, dairies, and electrocoating plants, as well as in water purification, biochemistry, and medical devices. Recently developed nanoselective filtration using PVDF membranes is 10 times more effective than conventional ultrafiltration (UF) for removing vimses from protein products of human or animal cell fermentations (218). PVDF protein-sequencing membranes are suitable for electroblotting procedures in protein research, or for analyzing the phosphoamino content in proteins under acidic and basic conditions or in solvents (219). 

Table 11. Nutritive Value of Leaf Protein Concentrates and Other Protein Products ...

Seed-Meal Concentrates and Isolates. Seed-meal protein products include flours, concentrates, and isolates, particularly soy protein products. These can be used as extenders for meat, seafood, poultry, eggs, or cheese (see Soybeans and other oilseeds). Detailed information on soybean and other seed-meal production processes is available (13,14,18). 

Products prepared from soy protein products and resembling chicken, ham, frankfurters, and bacon are available commercially. Soy protein isolates are used in place of milk proteins or sodium caseinate in products such as coffee creamers, whipped toppings, yogurt, and infant formulas (see Dairy substitutes). Soy protein products also are used in snacks and in baked foods. 

Hydration water, fat, and flavor binding gelation emulsifying foaming and whipping characteristics vary among different soy protein products and complete substitution of animal proteins by these products is not always possible (114). 

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). 

Functional properties of canola protein products can be improved by succinylation (130,131). Controlled acetylation can reduce undesirable phenoHc constituents as well (132). However, antinutrients in canola and other vegetable protein products such as glucosinolates, phytic acid, and phenoHc compounds have severely limited food appHcations of these products. 

In general, nonconventional protein foods must be competitive with conventional plant and animal protein sources on the bases of cost delivered to the consumer, nutritional value to humans or animals, functional value in foods, sensory quality, and social and cultural acceptability. Also, requirements of regulatory agencies in different countries for freedom from toxins or toxic residues in single-cell protein products, toxic glycosides in leaf protein products, pathogenic microorganisms, heavy metals and toxins in fish protein concentrates, or inhibitory or toxic peptide components in synthetic peptides must be met before new nonconventional food or feed protein products can be marketed. 

T. J. R. Harris, Protein Production by Biotechnology, Elsevier Science Pubhshers Ltd., New York, 1990. 

Biosynthesis. The biosynthesis of neuropeptides is much more complex and involves the multistep process of transcription of specific mRNA from specific genes, formation of a high molecular weight protein product by translation, post-translational processing of the protein precursor to allow for... 

A fermented-egg product (EEP), patented as an attractive bait for synanthropic flies, has been shown to be attractive to coyotes and repeUent to deer (79). Its components are variable, with relative concentrations of 77% fatty acids, 13% bases, and 10% (primarily) neutrals composed of at least 54 volatiles such as ethyl esters, dimethyl disulfide, and 2-mercaptoethanol. Synthetic formulations have been evaluated to find a replacement for a patented fermented-egg protein product that attracts coyotes and repels deer. Ten aUphatic acids (C-2 to C-8), four amines (pentyl, hexyl, heptyl, and trimethyl), dimethyl disulfide, 2-mercaptoethanol, and 54 more volatiles (C-1 to C-5 esters of C-1 to C-8 acids) have been tested as synthetic fermented egg (SEE) (80) in approximately the same proportions that are present in EEP. Weathering was a problem that caused decreased efficacy, which suggests trials of controUed-release formulations. Eourteen repeUents have been examined against white-taU deer in Peimsylvania in choice tests when treated onto sheUed com (81). 

The edible oilseed protein industry is comparatively small and is restricted to peanut and soybean proteins. One company manufactures partially defatted peanut flours made by hydraulic pressing. The products contain 40—42% protein. Production estimates for edible soybean proteins in the United States in 1993—1994 (56) and wholesale prices as of November 1995 are given in Table 15. 

Protein Products. The bulk of the meal obtained in processing of oilseeds is used as protein supplements in animal feeds. Since the 1960s appreciable amounts have been also converted into products for human consumption, the majority of which have been derived from defatted soybean flakes. 

Table 17. Compositions of Soybean Protein Products and Their Uses, wt %...

Streptokinase. The fibrinolytic activity of streptokinase, isolated from strains of hemolytic Streptococci, was first demonstrated in 1933 (63). Streptokinase is a secreted protein product inasmuch as filtrates free of demonstrable bacteria were found to dissolve fibrin clots with rapidity. 

FIG. 22-84 General stages in downstream processing for protein production indicating representative types of operations used at each stage. 

Cell Disruption Intracellular protein products are present as either soluble, folded proteins or inclusion bodies. Release of folded proteins must be carefully considered. Active proteins are subject to deactivation and denaturation, and thus require the use of gentle conditions. In addition, due consideration must be given to the suspending medium lysis buffers are often optimized to promote protein stability and protect the protein from proteolysis and deactivation. Inclusion bodies, in contrast, are protected by virtue of the protein agglomeration. More stressful conditions are typically employed for their release, which includes going to higher temperatures if necessaiy. For native proteins, gentler methods and temperature control are required. 

Factors to be considered in maldng the selection of chromatography processing steps are cost, sample volume, protein concentration and sample viscosity, degree of purity of protein product, presence of nucleic acids, pyrogens, and proteolytic enzymes. Ease with which different types of adsorbents can be washed free from adsorbed contaminants and denatured proteins must also be considered. 

Single-cell protein production Organic waste... 

Thi.s indicate.s whether combined. secretion-fu.sion gene. sy.stem.s have led to. secretion of die protein product from die cells, which simplifies its Isolation and pnrificadon. 

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