Protein capacity

Resin evaluation of both new and used resins (titration of total binding sites, total protein capacity, flow vs. pressure, particle size distribution, total organic carbon removed by cleaning procedures, and microbial and endotoxin analysis)... 

Ing cellulose acetate strip. This Instrument Is marketed by LKB Pro-dukter under the name Tachofrac. Kobayashl et al. (30) have also described preparative capillary ITP experiments using a syringe to extract fractions after migration across a potential gradient detector. Hjert n (31) has described a micropreparative zone electrophoretic technique In which the separation takes place In a capillary filled with a polyacrylamide gel. A flow of buffer past the end of the capillary sweeps the samples through a UV detector after which collection Is possible. This last method would seem to be the least useful because the smaller diameter tube limits the protein capacity to the ng to ug range. 

Reuse of Chromatography Resin, It is necessary to demonstrate that chromatographic media can be reused, cleaned, and sanitized [61]. Used resins receive additional analysis not required with new resins such as the titration of small ion binding capacity, measurement of total protein capacity, comparison of flow versus... 

Table 5-2. The relationship between pore size and specific ionic (m equivalents) or protein capacity (gmL column volume), as determined by frontal analysis for a range of strong anion exchangers based on a macroporous polystyrene matrix, PL-SAX.

Column Si. Size-exclusion chromatography columns are generally the largest column on a process scale. Separation is based strictly on diffusion rates of the molecules inside the gel particles. No proteins or other solutes are adsorbed or otherwise retained owing to adsorption, thus, significant dilution of the sample of volume can occur, particularly for small sample volumes. The volumetric capacity of this type of chromatography is determined by the concentration of the proteins for a given volume of the feed placed on the column. 

The total stationary-phase volume required to process a given feed stream is proportional to the inlet concentration and volume of the feed. For example, for a typical inlet concentration of protein of 10 g/L, in a 100 L volume of feed, a column volume of at least 100 L is needed for size-exclusion chromatography. In comparison, an ion-exchange column having an adsorption capacity of 50 g/L would only require 20 L of column volume for the same feed. 

Soft-wheat flours are sold for general family use, as biscuit or cake flours, and for the commercial production of crackers, pretzels, cakes, cookies, and pastry. The protein in soft wheat flour mns from 7 to 10%. There are differences in appearance, texture, and absorption capacity between hard- and soft-wheat flour subjected to the same milling procedures. Hard-wheat flour falls into separate particles if shaken in the hand whereas, soft-wheat flour tends to clump and hold its shape if pressed together. Hard-wheat flour feels slightly coarse and granular when mbbed between the fingers soft-wheat flour feels soft and smooth. Hard-wheat flour absorbs more Hquid than does soft-wheat flour. Consequently, many recipes recommend a variable measure of either flour or Hquid to achieve a desired consistency. 

The hide proteins differ in amino acid composition and physical stmcture. The principal amino acids (qv) of the hide proteins are hsted in Table 1. Of particular importance is the difference in the water solubiUty of the proteins. AH of the proteins are soluble in water when heated, and upon the addition of either strong acids or bases. Proteins (qv) are amphoteric, possessing both acid and base binding capacity. 

Albumen has the largest number of acid and basic groups. It is the most soluble of the proteins present in a hide. The albumen is not a fibrous material, however, and therefore has no value in the leather. Keratin is the protein of the hair and the outermost surface of the hide. Unless the hair is desired for the final product it is removed by chemical and/or physical means. The elastin has Htde acid- or base-binding capacity and is the least soluble of the proteins present. The lack of reactivity of the elastin is a detriment for most leather manufacture. The presence of elastin in the leather greatly limits the softness of the leather. 

Fig. 3. The pH dependence, where A, B, and C represent regions corresponding to the p-K s of glutamic and aspartic acids, lysine, and argenine, respectively, of (a) protein swelling, and (b) protein acid-binding capacity. Adapted from Ref. 3.

This resistance, inducible by low concentrations of dalbaheptides, is plasmid mediated and is transferable. Concomitant with the induction of resistance is the appearance or increased expression of a protein having a molecular weight of either 39,500 or 39,000. The enzymatic activity of this material has been postulated (112). Although the mechanism of resistance induction by dalbaheptides is unknown, different dalhabaheptides have different induction capacity. Vancomycin (39) is the most powerful inducer teicoplanin is a very weak inducer. 

Molecular Interactions. Various polysaccharides readily associate with other substances, including bile acids and cholesterol, proteins, small organic molecules, inorganic salts, and ions. Anionic polysaccharides form salts and chelate complexes with cations some neutral polysaccharides form complexes with inorganic salts and some interactions are stmcture specific. Starch amylose and the linear branches of amylopectin form inclusion complexes with several classes of polar molecules, including fatty acids, glycerides, alcohols, esters, ketones, and iodine/iodide. The absorbed molecule occupies the cavity of the amylose helix, which has the capacity to expand somewhat to accommodate larger molecules. The starch—Hpid complex is important in food systems. Whether similar inclusion complexes can form with any of the dietary fiber components is not known. 

Ultrafiltration (qv) (uf) is increasingly used to remove water, salts, and other low molecular-weight impurities (21) water may be added to wash out impurities, ie, diafiltration. Ultrafiltration is rarely used to fractionate the proteins because the capacity and yield are too low when significant protein separation is achieved. Various vacuum evaporators are used to remove water to 20—40% dry matter. Spray drying is used if a powdery intermediate product is desired. Tyophilization (freeze-drying) is only used for heat-sensitive and highly priced enzymes. 

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