Ultrafiltration yield

Even though enzymatic conversion is not too effective, it is possible to prepare semipermeable membranes whose ultrafiltration yields are higher than those of passive membranes.74 75 Ultrafiltration experiments of cheese whey through cellulosic membranes to which papain was covalently bound, show that flux decay curves of enzymatic membranes are even less sensitive to pH changes.74... 

Pish protein concentrate and soy protein concentrate have been used to prepare a low phenylalanine, high tyrosine peptide for use with phenylketonuria patients (150). The process includes pepsin hydrolysis at pH 1.5 ptonase hydrolysis at pH 6.5 to Hberate aromatic amino acids gel filtration on Sephadex G-15 to remove aromatic amino acids incubation with papain and ethyl esters of L-tyrosine and L-tryptophan, ie, plastein synthesis and ultrafiltration (qv). The plastein has a bland taste and odor and does not contain free amino acids. Yields of 69.3 and 60.9% from PPG and soy protein concentrate, respectively, have been attained. 

Ultrafiltration equipment suppHers derive K empirically for their equipment on specific process fluids. Flux J is plotted versus log for a set of operation conditions in Figure 6 K is the slope, and is found by extrapolating to zero flux. Operating at different hydrodynamic conditions yields differently sloped curves through C. ... 

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. 

Membrane Processes Membrane processes are also used diafiltration is convenient for the removal of small contaminating species such as salts and smaller proteins, and can be combined with subsequent steps to concentrate the protein. Provided that proper membrane materials have been selected to avoid protein-membrane interactions, diafiltration using ultrafiltration membranes is typically straightforward, high-yielding and capital-sparing. These operations can often tolerate the concentration or the desired protein to its solu-bihty limit, maximizing process efficiency. 

In addition, our results suggest that removal of hpids improves both yield characteristics and elemental characteristics. Recent work by Liden et al. (1995) suggests that the methanol-chloroform method used here is more effective than other methods, such as treatment with NaOH solution, or the maintenance of an acidic environment and ultrafiltration of products during collagen extraction. It is speculated that the presence of hpids in archaeological bone samples may interfere with the acid hydrolysis of protein during... 

Aim of this work was to optimise enzymatic depolymerization of pectins to valuable oligomers using commercial mixtures of pectolytic enzymes. Results of experiments in continuous and batch reactor configurations are presented which give some preliminary indications helpful to process optimisation. The use of continuous reactors equipped with ultrafiltration membranes, which assure removal of the reaction products, allows to identify possible operation policy for the improvement of the reaction yield. 

The purification of a product p from an impurity i by an ultrafiltration process is shown in Fig. 20-59 and Eq. (20-72), where Cjo and C o are the initial concentrations (g/L) of the two components, Y is the yield of product in the retentate, and r / = selectivity = S,/Sp, the ratio of passages. High yields are obtained in purifying out small solutes (high selectivity) but are compromised in removing larger impurities with similar passages to the product. 

These estimates, though approximate, established that — excluding sample consumption for testing — the yield could not have been less than 20% and perhaps as much as 50%. Since another 10 pg of hementin were known to have been lost into the filtrate of the initial ultrafiltration and another 5 to 10 pg into IEC peaks II and III, no less than 40% and up to 80% of the material was accounted for. 

An alternative to extraction crystallization is used to obtain a desired enantiomer after asymmetric hydrolysis by Evonik Industries. In such a way, L-amino acids for infusion solutions or as intermediates for pharmaceuticals are prepared [35,36]. For example, non-proteinogenic amino acids like L-norvaline or L-norleucine are possible products. The racemic A-acteyl-amino acid is converted by acylase 1 from Aspergillus oryzae to yield the enantiopure L-amino acid, acetic acid and the unconverted substrate (Figure 4.7). The product recovery is achieved by crystallization, benefiting from the low solubility of the product. The product mixture is filtrated by an ultrafiltration membrane and the unconverted acetyl-amino acid is reracemized in a subsequent step. The product yield is 80% and the enantiomeric excess 99.5%. 

Ultrafiltration may also be utilized to achieve a number of other objectives. As discussed above, it may yield a limited degree of protein purification and may also be effective in depyrogenating solutions. This will be discussed further in Chapter 7. The technique is also widely used to remove low molecular mass molecules from protein solutions by diafiltration. 

Virtually all the mercury in plasma is protein-bound [17, 18]. Haemolyzed samples of blood from rats given radioactive mercuric chloride yielded less than 0.5% ultrafiltrate mercury. The distribution between different plasma-protein fractions varied with dose, time after, and type of, administration [19-21]. 

In the ultrafiltration of a protein solution of concentration 0.01 kg/m3, analysis of data on gel growth rate and wall concentration yields the second order relationship ... 

This simplified calculation is used to illustrate basic computational techniques. It assumes that all of the Fe(OH)3(aq) is a true solute. The quality of this assumption is a matter of debate as at pH 8, Fe(OH)3(aq), tends to form colloids. Thus, laboratory measurements of ferrihydrite solubility yield results highly dependent on the method by which [Fe(lll)]jQ(gj is isolated. Ultrafiltration techniques that exclude colloids from the [Fe(lll)]jQjgj pool produce very low equilibrium solubility concentrations, on the order of 0.01 nM. This is an important issue because a significant fraction of the iron in seawater is likely colloidal, some of which is inorganic and some organic. In oxic... 

In contrast to solid-phase Suzuki couphng, very low amounts of the Pd-catalyst (0.2 mol%) were sufficient and high conversions (87-99%) to biaryls (65) were obtained to yield relatively pure products (>90%, GC/MS, NMR) after ultrafiltration. In some cases most of the polymer supported boronic compound precipitated during the reaction and therefore no further purification was required. Nonetheless, quantitative removal of catalyst traces was not yet possible with either work-up protocol. 

Several variations on these production methods also exist, such as the use of immobilized CGTase (2i, 22), continuous ultrafiltration 23) and the use of isoamylase to increase CD yield. Variations of purification methods include the addition of glucoamylase to degrade non-CD starch hydrolysates to simply separation and the use of various S3mthetic ion exchange resins in chromatographic separations 24-26) and acuity columns (27),... 

Fructan was harvested by precipitation from the culture broth by addition of ethanol or isopropanol. Acetone and methanol can also be used. The yield and consistency of the product varied depending on the amount of alcohol added. The fructan started to precipitate at the medium/alcohol v/v ratio of 1 1.2, and the yield peaked at about 1 1.5. Further increase in the ratio hardened the fructan and made the product less fluid. Slightly less isopropanol was needed than ethanol to precipitate levan (fructan). Although most of the bacterial cells, unfermented sugars, and other solubles remained in the aqueous alcohol phase, pre-removal of microbial cells by centrifuging was needed to obtain a pure form of fructan. The product was further purified by repeated precipitation and dissolution in water, followed by dialysis or ultrafiltration. The final product was an... 

The smallest functional unit of the kidney is the nephron. In the glomerular capillary loops, ultrafiltration of plasma fluid into Bowman s capsule (BC) yields primary urine. In the proximal tubules (pT), approx. 70% of the ultrafiltrate is retrieved by isoosmotic reabsorption of NaCl and water. In the thick portion of the ascending limb of Henle s loop (HL), NaCl is absorbed unaccompanied by water. This is the prerequisite for the hairpin countercurrent mechanism that allows build-up of a very high NaQ concentration in the renal medulla In the distal tubules (dT), NaCl and water are again jointly reabsorbed. At the end of the nephron, this process involves an aldosterone-controlled exchange of Na+ against 1C or H. In the collecting tubule (C), vasopressin (antidiuretic hormone, ADH) increases the epithelial permeability for water, which is drawn into the hyperosmolar milieu of the renal medulla and thus retained in the body. As a result, a concentrated urine enters the renal pelvis. 

In the synthesis of A-acetyllactosamin from lactose and A-acetylglucosamine with (3-galactosidase (289,290), the addition of 25 vol% of the water-miscible ionic liquid [MMIM][MeS04] to an aqueous system was found to effectively suppress the side reaction of secondary hydrolysis of the desired product. As a result, the product yield was increased from 30 to 60%. Product separation was improved, and the reuse of the enzymatic catalyst became possible. A kinetics investigation showed that the enzyme activity was not influenced by the presence of the ionic liquids. The enzyme was stable under the conditions employed, allowing its repeated use after filtration with a commercially available ultrafiltration membrane. 

Optimal fermentation parameters have been well established and air-lift, stirred tank, and hollow fibre systems have all been used. At commercial scale, fermentation volumes in excess of 1000 litres can be used, which can yield 100 g or more of final product. While hybridoma growth is straightforward, production levels of antibody can be quite low compared with ascites-based production systems. Typically, fermentation yields antibody concentrations of 0.1-0.5 mg/ml. Removal of cells from the antibody-containing media is achieved by centrifugation or filtration. An ultrafiltration step is then normally undertaken in order to concentrate the filtrate by up to 20-fold. 

Cabral and coworkers [253] have investigated the batch mode synthesis of a dipeptide acetyl phenylalanine leucinamide (AcPhe-Leu-NH2) catalyzed by a-chymotrypsin in a ceramic ultrafiltration membrane reactor using a TTAB/oc-tanol/heptane reverse micellar system. Separation of the dipeptide was achieved by selective precipitation. Later on the same group successfully synthesized the same dipeptide in the same reactor system in a continuous mode [254] with high yields (70-80%) and recovery (75-90%). The volumetric production was as high as 4.3 mmol peptide/l/day with a purity of 92%. The reactor was operated for seven days continuously without any loss of enzyme activity. Hakoda et al. [255] proposed an electro-ultrafiltration bioreactor for separation of RMs containing enzyme from the product stream. A ceramic membrane module was used to separate AOT-RMs containing lipase from isooctane. Application of an electric field enhanced the ultrafiltration efficiency (flux) and it further improved when the anode and cathode were placed in the permeate and the reten-tate side respectively. 

The metalloprotease thermolysin, obtained from Bacillus thermoproteolyticus, a strain of B. stearothermophilus, is used as a crude preparation in an aqueous medium. The enzyme is recovered from the reaction mixture by ultrafiltration with a yield of >95%. 

After the mild-hydrolysis step at 70°, the sialic acids liberated are removed from the sample by dialysis or ultrafiltration at 2°, and the macromolecular material is rehydrolyzed, using, however, the stronger acidic conditions of 0.1 M acid. The dialysis time ranges between 6 and 24 h, depending on the volume and viscosity of the hydrolysis mixture. Therefore, the optimum dialysis time should be evaluated by determinations of sialic acid in the eluate, or by addition of a trace of radioactive Nen5Ac. The dialyzates, or filtrates, are combined, and processed as will be described. By using this procedure, the overall yield of purified sialic acids is 70-80%, and the loss of O-acetyl groups107 is 40%. 

Ion-exchange chromatography proteins are adsorbed on an ion exchanger, washed free of lactose and salts and then eluted by pH adjustment. The eluate is freed of salts by ultrafiltration and spray-dried to yield whey protein isolate, containing about 95% protein. 

Parrish, F. W., Sharpies, P. M., Hoagland, P. D. and Woychik, J. H. 1979, Demineralization of cheddar whey ultrafiltrate with thermally regenerable ion-exchange resins Improved yield of a-lactose monohydrate. J. Dairy Sci. 44, 555-557. 

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