Precipitation, maximum

Figure 7.5 Antigen-antibody reaction. Maximum precipitation occurs when the antigen and antibody are present in equivalent amounts and is due to the formation of large lattice structures. On either side of the equivalence zone the amount of precipitation is reduced because the aggregates are smaller and more soluble.

Gels are used in immunoprecipitation techniques to stabilize the precipitate, enabling both the position and the area of the precipitate to be measured. The point has already been made that maximum precipitation occurs when the equivalent proportions of both antigen and antibody are available. Hence, if a high concentration of antigen is permitted to diffuse into a gel that contains a uniform concentration of antibody, at some point in the concentration gradient of antigen that is... 

When the amount of ethyl alcohol exceeds 18 per cent., the addition of water causes a precipitation of iodine, at lower alcohol cone, there is no precipitation. The maximum precipitation occurs when just enough water is added to bring the alcohol cone, to 18 per cent. 

Commercial casein is usually manufactured from skim milk by precipitating the casein through acidification or rennet coagulation. Casein exists in milk as a calcium caseinate-calcium phosphate complex. When acid is added, the complex is dissociated, and at pH 4.6, the isoelectric point of casein, maximum precipitation occurs. Relatively little commercial casein is produced in the United States, but imports amounted to well over 150 million lb in 1981 (USDA 1981C). Casein is widely used in food products as a protein supplement. Industrial uses include paper coatings, glues, plastics and artificial fibers. Casein is typed according to the process used to precipitate it from milk, such as hydrochloric acid casein, sulfuric acid casein, lactic acid casein, coprecipitated casein, rennet casein, and low-viscosity casein. Differences... 

Because derivatization impaired proteolysis, its effect on endogenous ribonclease was studied. Ribonuclease activity was inhibited with increasing succinylation and dropped sharply at an anhydride to protein ratio of 0.8 where 80% of e-NH2 groups of the total protein were succinylated (Fig. 5). Because the ribonuclease was inactivated, an increased nucleic acid content in the precipitated proteins was expected. However, we observed less nucleic acid (NA) in precipitated succinylated protein than in the non-modified controls. Maximum precipitation of succinylated protein occurred around pH 4.5 and contained only 1.8% nucleic acid on a... 

The previous equations can be used to determine the conditions that will allow maximum precipitation of the solid represented by Al(OH)3. The maximum precipitation of A1(0H)3 will produce the utmost clarity of the treated water. To allow for this maximum precipitation, the concentrations of the complex ions Al(OH), Al7(OH)i7, A1,3(0H)34, A1(0H)4, and Al2(OH)2" and Al " must be held to a minimum. This will involve finding the optimum pH of coagulation. This optimum pH may be determined as follows ... 

In the application of the previous equations in coagulation treatment of water, conditions must be adjusted to allow maximum precipitation of the solid represented by A1(OH)3(s). To allow for this maximum precipitation, the concentrations of the complex ions must be held to a minimum. 

The complexes are FeOH and Fe(OH)3. Also note that the OH ion is a participant in these reactions. This means that the concentrations of each of these complex ions are determined by the pH of the solution. In the application of the above equations in an actual coagulation treatment of water, conditions must be adjusted to allow maximum precipitation of the solid represented by Fe(OH)2(j). To allow for this maximum precipitation, the concentrations of the complex ions must be held to the minimum. The values of the equilibrium constants given above are at 25°C. 

Optimum pH—The pH at which maximum precipitation occurs or at which the concentration of the species to be removed is at the lowest. 

State occurs when 2 to 3 antibody molecules are present for each antigen molecule produces maximum lattice formation and therefore maximum precipitate. 

As indicated in Table 3, increased ionic strength not only reduces the maximum precipitation possible, but also increases the polymer dosage requirement for optimum precipitation. This may be a result of the shielding effect attributed to high levels of counterions around charged macromolecules. A higher concentration of polymer-ionic groups is required to displace the counterions around the protein molecule. 

Increased ionic strength levels serve to increase the polymer dosage requirement, reduce the maximum precipitation possible, and reduce the effect of precipitation pH on protein recovery. 

It is shown that the zones of high NDVI values appear to correspond (in general) to high precipitation areas. However, some differences are evident. For example, the zone of rather high NDVI in the lower course of the Amudarya coincides with the zone of extremely low precipitation (the Amudarya seems to be an exclusive source of water for the plants growing there). Both GPCC and NDVI exhibit pronounced seasonal variation, with maximum precipitation in March and maximum NDVI in May-June (Fig. 16). 

Sodium oxalate combined with Number of well with maximum precipitate Drops of oxalate solution Drops of Group 2 ion solution... 

Syncompactional, mesogenetic euhedral calcite has 6 0 values between -12.4%o and -6.6%o (Table 1) and higher Mn contents than eogenetic calcite (r = + 0.76) (Fig. 21b). Assuming that precipitation occurred from moderately evolved meteoric pore waters with an average S 0 composition similar to that of the present-day average formation water (-3%o), these late calcites must have precipitated at temperatures of 30-70°C (Fig. 19). The maximum precipitation temperature of mesoge-... 

The acetate buffer is set at pH 4.9 because 4.9 is the pi of BSA and thus affords maximum precipitation of the tannin/protein complexes formed during the precipitation reaction. Coincidentally pH 4.9 is particularly good for measuring absorbance due to polymeric pigments because the anthocyanins have their minimum absorbance at that pH (d). Since any remaining monomeric anthocyanins are bleached with bisulfite, this procedure assures that all of the remaining 520 nm absorbance is due to polymeric pigments (LPP + SPP). 

The dialyzed protein from the outer level was filtered and acidified with 1 N HCl. Maximum precipitation occurred at about pH 5.5, leaving a clear supernatant fluid. The precipitate was washed with water and redispersed in 6 M urea. The clear supernatant liquid at pH 5.5 was filtered and further acidified. A cloudy precipitate forms at about pH 5, the precipitation attaining a maximum near pH 4.5. This settles out on standing. Thus the primary solution of the epidermal proteins in 6 M urea is divided into two main fractions—a coarse, flocculent precipitate at pH 5.5 and a fine, granular precipitate at pH 4.5. The first precipitate can be dissolved in urea, dialyzed and reprecipitated at pH 5.5 many times. For the present purposes the processes were repeated three times. The precipitate at pH 4.5 can be redissolved by adjusting the pH to 7 with NaOH these processes were also repeated three times. 

Ihe ccmposition of urea cottplexes is usually represented by the ratio of moles of urea per mole of included coitpound. Ihe ratio is constant for any given ootrplex and is ind )endent of the relative concentrations of the partners previous to adduct formation and of the tenperature that is, urea adducts must be considered as true conopounds and not as mixed crystals. Doao[art (17) indicated that there was a considerable selectivity in the fatty acids precipitated vhen the moles of urea present were less than the quantity required for maximum precipitation. For exanple, if the mole ratio of urea to fatty acids was 4.6, then the fatty acids obtained from the complex are hi ily saturated. However, at hi er mole ratios, not only saturated fatty acids, but also seme portion of the unsaturated fatty acids present were exmplexed 1 urea. Virtually all the saturated and monoenoic fatty acids are precipitated at a mole ratio in the region of 12 1 to 13 1 (Table V). 

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