Limitations of Affinity Chromatography: Solvolytic Detachment of Ligands from Polymeric Supports

摘要: Ligands of the RNH2 type which are covalently bound to agarose, cellulose, or cross-linked dextranes by conventional cyanogen bromide method slowly detached from their supports solvolytic processes occurring above pH 5 in aqueous surroundings. At values between and 10, free ligands, RNH2, appear solution. Above about carbamyl derivative ligand, RNHCONH2, is main product. Dilute ammonia releases iminocarbamyl derivatives, RNHC(NH)NH2. The latter compound has also been observed tris(hydroxymethyl)-aminomethane buffers at 8 9. Possible reaction mechanisms have formulated on basis structures suggested Axen & Ernback for activated substituted polysaccharides. attached polyacrylamide gels (A) through amide bonds carboxyl groups carrier, RNHCO·A, released slower rates invariably as free, unsubstituted ligand molecules. release be general independent particular structure. We therefore advise caution with all experiments that can adversely influenced presence ligands (e.g. localization hormone receptors cell surface). pH5, sepharose-bound 8-(ϵ-aminocaproyl-β-aminoethylthio)-adenosine-3′, 5′-cyclo-monophosphate removes cyclic 3′, 5′-adenosine-monophosphate-binding proteins solutions, but corresponding does not (pH 7).