Protein yield

The reaction of dextrose with a nitrogen-containing compound, eg, amino acids or proteins, yields a series of intermediates which form pigments of varied molecular weight (Maikard reaction). The type of pigments produced is dependent on reaction conditions such as pH, temperature, and concentration of reactants. 

Those with a normal diet take in food in the forms of carbohydrates, fats and proteins. Because it has a low water content and produces so many ATP molecules, fat yields 9.3 Calories per gram while carbohydrates and proteins yield less than half as much (4.1 and 4.3 calorics per gi-am respectively). Thus, we get a huge number of calories from a small quantity of fat eaten. The average person in the United States has a diet with 50 percent of the calories in the form of carbohydrates, 35 percent in the form of fat and 15 percent in the form of protein. We need about 1 gram of protein per kilogram of body weight per day to replace body proteins that are broken down. A 70 kg person... 

A 1.00-mg sample of a pure protein yielded on hydrolysis 0.0165 mg of leucine and 0.0248 mg of isoleucine. What is the minimum possible molar mass of the protein (MM leucine = MM isoleucine = 131 g/mol)... 

The ESI-MS of an intact protein yields a series of ions with mfc values corresponding to sequentially charged species (Fenn et al., 1989). Algorithms and software for the deconvolution of these peaks into a single neutral mass have been available for many... 

The improvement of its activity and stability has been approach by the use of GE tools (see Refs. [398] and [399], respectively). A process drawback is the fact that the oxidation of hydrophobic compounds in an organic solvent becomes limited by substrate partition between the active site of the enzyme and the bulk solvent [398], To provide the biocatalyst soluble with a hydrophobic active site access, keeping its solubility in organic solvents, a double chemical modification on horse heart cytochrome c has been performed [400,401], First, to increase the active-site hydrophobicity, a methyl esterification on the heme propionates was performed. Then, polyethylene glycol (PEG) was used for a surface modification of the protein, yielding a protein-polymer conjugates that are soluble in organic solvents. 

The concentration of milk protein is controlled by the rate of milk protein synthesis (milk protein yield) in relation to milk yield (milk volume). The... 

Several other fluorescent proteins have been isolated from a variety of species. We will briefly discuss the variants with the most optimal spectroscopic properties. A true orange fluorescent protein was isolated from the stony coral Fungia concinna, with good absorbance and a quantum yield of 0.45. Targeted mutagenesis was used to monomerize the protein, yielding mKO with an absorbance of 51,600 M-1 cm 1 and a quantum yield of 0.74 [84, 85], The crystal... 

Figure 1.63 Deprotection with hydroxylamine of the acetylated thiol of SATA-modified proteins yields a free sulfhydryl group.

Figure 18.4 The reaction of bis-NHS-PEG5 with amines on proteins yields amide bond linkages with amine-containing molecules.

Figure 28.12 Sulfo-SBED first is used to label a bait protein through reaction of the sulfo-NHS ester with available amine groups on the protein, yielding an amide bond linkage. This labeled bait protein then is added to a sample containing proteins that potentially could interact with the bait. After an incubation period, the sample is exposed to UV light to photoactivate the phenyl azide group. This reaction causes any interacting prey proteins to be crosslinked with the bait protein, forming a complex containing a biotin affinity tag.

Although plant cell culture is not as cost effective as plant cultivation in the open field, it will become an economical process if higher protein yields can be achieved [58]. The cultivation medium of plants is chemically defined, consisting of a carbon source, minerals, vitamins and phytohormones [69]. Furthermore, it is protein-free and relatively inexpensive. In contrast, animal cells often require complex supplements such as fetal calf serum and/or expensive growth factors, although serum-free cultivation is possible in case of Chinese hamster ovary (CHO) cells [70]. 

Increased transcription levels are assumed to result in increased protein synthesis. One approach to reach this goal is to raise the transgene copy number by the use of amplification-promoting sequences derived from a spacer sequence of tobacco ribo-somal DNA [95]. Posttranscriptional processes such as capping, splicing and polya-denylation are important for high protein yields, and it is also important to maximize mRNA stability [84]. 

Fig. 8.9 Enzyme linked immunoassays, with protein yields expressed as %TSP and pg of FI V per gram of fresh leaf material. For the continuous illumination experiment, leaf material was sampled on days 0, 1, 3 and 5. Young, mature, and old samples were taken for each experiment. The figure shows average levels of FIVantigen for Samples 1 -4 (Day 0 (1) young, (2) mature, (3) old, and (4) wild type leaf samples) Samples 5-8 (Day 1 (5) young, (6) mature,...

One of the most important considerations for the improvement of protein yields is subcellular protein targeting, because the compartment in which a recombinant protein accumulates strongly influences the interrelated processes of folding, assembly and post-translational modification. All of these contribute to protein stability and hence help to determine the final yield [88]. 

Lowry method uses a combination of the Biuret copper-based reagent and the Folin-Ciocalteau reagent, which contains phosphomolybdic-phosphotungstic acid. Reagents react with protein, yielding a blue colour that displays an absorbance maximum at 750 nm... 

Bradford reagent contains the dye Coomassie blue G-250 in an acidic solution. The dye binds to protein, yielding a blue colour that absorbs maximally at 595 nm Copper-containing reagent that, when reduced by protein, reacts with bicinchonic acid yielding a complex that displays an absorbance maximum at 562 nm Essentially involves initial precipitation of protein out of solution by addition of trichloroacetic acid. The protein precipitate is redissolved in NaOH and the Lowry method of protein determination is then performed Interaction of silver with protein - very sensitive method... 

When oxidized, 1 g of protein yields four calories. Including the caloric contribution from protein in calorie calculations is controversial therefore, PN calories can be calculated as either total or nonprotein calories. 

Unfortunately, the description of amyloid fibrils given above is simplistic since in vitro self-assembly of amyloid peptides and proteins yields polymorphic structures, as has been commonly observed in the past for other protein assemblies such as actin filaments (Millonig et al, 1988) and intermediate filaments (Herrmann and Aebi, 1999). On the one hand, assembly polymorphism complicates the characterization of fibril structure. On the other hand, it offers some insight into fibril formation. For this reason a more rational understanding of amyloid fibril formation at the molecular level is a key issue in the field of amyloidosis. 

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