Dialysis reaction products

There appear to be several possible side-reactions which may produce some unwanted products. [ C-]Formaldehyde is reduced to [ C]methanol to a small extent, but this reaction product can be removed by dialysis of... 

After cooling to room temperature, the sugar-dendrimer derivative may be precipitated with a large volume of methanol. The precipitate may be purified from reaction products by dialysis against water or buffer using a membrane with a molecular weight cutoff of 3500 Daltons. The final product may be stored frozen or lyophilized to a white powder. 

Methods. Reaction with DESO4 The hydroxyl functionality of HPL was reduced by reaction with diethyl sulphate in accordance with earlier work (13). The reaction product was isolated by liquid-liquid extraction and dialysis. 

In the previous examples the membranes have been considered generally as semiperineable barriers for the separation of small molecules from bigger ones. When in parallel to the separation a chemical reaction takes place in the bulk solution or in the membrane itself, the system may be identified as a true membrane reactor. A classical example is a stirred-tank enzymatic reactor connected by a continuous recirculation loop to an ultrafiltration or dialysis unit. Such a system, when well designed, permits the continuous removal of the reaction products from the bulk solution without loss of enzyme (or the insoluble or macromolecular substrate ). 

A mixture of equal parts of SiHCls and benzene is poured with stirrir into 10 times its volume of ice-water mixture. The SiHClg must be carefully fractionated to free it of SiCl. After a while, the reaction product is filtered off and purified by repeated suspension and washing with water. Complete removal of chlorine is difficult and is possible only by dialysis, as described by Schwarz and Souard. The product prepared as above still contains 0.5% Cl after three washings. It is dried overnight in a stream of air at 125°C. 

The radioactive material is separated from the enzyme by dialysis against 20 volumes of deionized water. Salts are removed from the dialyzate by filtration over Dowex 50 X 8 (H form) and neutralization of the acid in the filtrate with Dowex 1X8 (OH form). If denatura-tion is necessary, it is advised to remove the denaturant by dialysis before the hydroxylamine treatment. The desalted solution containing the released label is concentrated to dryness, and the reaction product is identified by descending paper chromatography in acetone/water 6 1 and n-butanol/acetic acid/water 4 1 P and cocrystallization with authentic reference substances. Three reaction products can be expected from racemic conduritol B epoxide, provided the reacting group on the enzyme is a carboxylate ion (-j-)-cliiro-inositol, (—)-cAiro-inositol, and scyllo-inositol. 

The yields of this reaction are typically 40—80%. C-nmr studies (41) indicate that the reaction is a second-order process between polyacrylamide and dim ethyl am in om eth an ol, which is one of the equiUbrium products formed in the reaction between formaldehyde and dimethylamine [124-40-3] C2H2N. The Mannich reaction is reversible. Extensive dialysis of Mannich polyacrylamides removes all of the dimethyl aminomethyl substituents (42). 

Recent applications of HPAEC-PAD are many and varied. A representative list includes quantitation of polyglucose metabolites in plasma of dialysis patients,148 analysis of heat-treated milk,149 carbohydrate content in lipopolysaccharides,150 phosphorylated sugars in tissue samples,151 composition of soybean meal,152 carbohydrate composition of recombinant modified tissue plasminogen activator,153 analysis of cyclization products from an enzyme reaction,154 carbohydrate content of glycoconjugate vaccines,155 and monitoring of patients with rheumatoid arthritis.156... 

Separate modified protein from unreacted SATA and reaction by-products by dialysis against 50 mM sodium phosphate, pH 7.5, containing ImM EDTA or by gel filtration on a Sephadex G-25 column (Pharmacia) using the same buffer. 

Purify the modified protein from reaction by-products by dialysis or gel filtration using 50mM sodium phosphate, 0.15M NaCl, pH 7.2. 

Remove unreacted N-acetyl homocysteine thiolactone and reaction by-products by gel filtration or dialysis against lOmM sodium phosphate, 0.15M NaCl, lOmM EDTA, pH 7.2. Other buffers suitable for individual protein stability may be used as desired. For the silver nitrate-containing reaction, removal of the silver-thiourea complex may be done by adsorption onto Dowex 50, and the protein subsequently eluted from the resin by 1M thiourea. Removal of the thiourea then may be done by gel filtration or dialysis. 

Remove excess reagent and reaction by-products by dialysis or gel filtration using 0.1M sodium phosphate, 0.15M NaCl, lOmM EDTA, pH 7.5. For chromatographic separation, use a desalting gel filtration support such as the Zeba desalting spin columns (Thermo Fisher) or the equivalent. The SAMSA-modified protein may be stored at -20°C until needed. 

Separate excess cystamine and EDC (and reaction by-products) from the modified protein by dialysis or gel filtration using 10 mM sodium phosphate, 0.15M NaCl, pH 7.2. A desalting column may be used for the gel filtration procedure (i.e., Zeba spin columns from Thermo Fisher). 

Purify the reduced IgG from excess 2-mercaptoethylamine and reaction by-products by dialysis or gel filtration using a desalting resin. All buffers should contain 1-10 mM EDTA to preserve the free sulfhydryls from metal-catalyzed oxidation. The sulfhydryl-containing half antibody now may be used in conjugation protocols that use —SH-reactive heterobifunctional crosslinkers (Chapter 5, Section 1). 

Purify the modified protein away from excess reagent and reaction by-products by gel filtration using a desalting column or dialysis. 

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