Ion-exchange Sephadex

Sephadex beads for gel filtration ion-exchange Sephadex resins... 

Redgwell, R.J. (1980) Fractionation of plant extracts using ion-exchange Sephadex, Anal Biochem. 107, 44-50. 

Garcia Jimenez et al. proposed the analysis of additive mixtures by FIA, including a monolithic minicolumn placed in Figure 24.5 or before the flow cell of a monochannel FIA setup with no prior derivatization reaction. Accordingly, they developed flowthrough spectrophotometric sensors (UV absorption) based on the transient retention of analytes on several solid phases, namely, ion exchanger Sephadex DEAE A-25 [73], silica... 

Sephadex A trade name for an insoluble hydrophilic substance prepared by cross-linking dextran, and used in gel filtration. It can also be linked to acidic or basic groups for ion exchange or to alkanes for the chromatography of lipophilic compounds. 

Recovery and Purification. The dalbaheptides are present in both the fermentation broth and the mycelial mass, from which they can be extracted with acetone or methanol, or by raising the pH of the harvested material, eg, to a pH of 10.5—11 for A47934 (16) (44) and A41030 (41) and actaplanin (Table 2) (28). A detailed review on the isolation of dalbaheptides has been written (14). Recovery from aqueous solution is made by ion pair (avoparcin) or butanol (teicoplanin) extraction. The described isolation schemes use ion-exchange matrices such as Dowex and Amberlite IR, acidic alumina, cross-linked polymeric adsorbents such as Diaion HP and Amberlite XAD, cation-exchange dextran gel (Sephadex), and polyamides in various sequences. Reverse-phase hplc, ion-exchange, or affinity resins may be used for further purification (14,89). 

Sephadex. Other carbohydrate matrices such as Sephadex (based on dextran) have more uniform particle sizes. Their advantages over the celluloses include faster and more reproducible flow rates and they can be used directly without removal of fines . Sephadex, which can also be obtained in a variety of ion-exchange forms (see Table 15) consists of beads of a cross-linked dextran gel which swells in water and aqueous salt solutions. The smaller the bead size, the higher the resolution that is possible but the slower the flow rate. Typical applications of Sephadex gels are the fractionation of mixtures of polypeptides, proteins, nucleic acids, polysaccharides and for desalting solutions. 

Adenosine 5"-[P-thio]diphosphate tri-lithium salt [73536-95-5] M 461.1. Purified by ion-exchange chromatography on DEAE-Sephadex A-25 using gradient elution with 0.1-0.5M triethylammonium bicarbonate. [Biochem Biophys Acta 276 155 7972.]... 

Bromelain (anti-inflammatory Ananase from pineapple) [37189-34-7] Mr 33 000, [EC 3.4.33.4]. This protease has been purified via the acetone powder, G-75 Sephadex gel filtration and Bio-Rex 70 ion-exchange chromatography and has Aj 20.1 at 280nm. The protease from pineapple hydrolyses benzoyl glycine ethyl ester with a Km (app) of 210mM and kcat of 0.36 sec. [Murachi Methods Enzymol 19 273 1970 Balls et al. nd Eng Chem 33 950 1941.]... 

Coiicin E (from E.coli) [11032-88-5], Purified by salt extraction of extracellular-bound colicin followed by salt fractionation and ion-exchange chromatography on a DEAE-Sephadex column, and then by CM-Sephadex column chromatography [Schwartz and Helinski J Biol Chem 246 6318 1971],... 

Corticotropin [92307-52-3] polypeptide Mr -4697. Extract separated by ion-exchange on CM-cellulose, desalted, evapd and lyophilised. Then run on gel filtration (Sephadex G-50) [Lande et al. Biochemical Preparations 13 45 1971 Esch et al. Biochem Biophys Res Commun 122 899 1984],... 

Chromatographic resolution of metal complexes on Sephadex ion exchangers. Y. Yoshikawa and K. Yamasaki, Coord. Chem. Rev., 1979, 28, 205-229 (98). 

As an example, consider the separation of the creatine kinase isoenzymes, MM, MB, and BB. Mercer has used classical ion-exchange chromatography (DEAE - Sephadex - A50) for the resolution of these three isoenzymes (44) To speed up the separation and ultimately to allow an automated analysis,... 

Table II. Carbohydrate compositions (weight percentage) of individual oligomer peaks purified (QAE-Sephadex or HPLC ion-exchange separation, respectively) from mixtures of citrus pectin oligomers or B fruit extracts Compositions shown are for peaks whose biological activity is described in Figure 4. Uronic acid values are based on colorimetric assay. Proportions of neutral sugars were determined by GC and adjusted so that totals equal 100%. In fact, some oligomers (G7 peaks 8, 9 and 10. B extract peak 10) produced small (less than 1 % of the total integrated area), unknown peaks in the GC chromatograms.

Figure 17 High performance vs. classical ion exchange in cation exchange of crys-tallins. (a) SP-Sephadex column, 0.5ml/min. The separation time was 7 hr. (b) SynchroPak CM300, 1 ml/min. The separation time was 20 min. (Reproduced with permission of Academic Press from Siezen, R. J., Kaplan, E. D., and Anello, R. D., Biochem. Biophys. Res. Comm., 127, 153, 1985.)...

Renberg [35] used an ion-exchange technique for the determination of chlorophenols and phenoxy acetic acid herbicides in soil. In this method the soil extracts are mixed with Sephadex QAE A-25 anion exchanger and the adsorbed materials are then eluted with a suitable solvent. The chlorinated phenols are converted into their methyl ethers and the chlorinated phenoxy acids into their methyl or 2-chloroethyl esters for gas chromatography. 

The sample is shaken with 0.2m sodium hydroxide (4ml g-1 soil) in a test tube for 30min. After centrifugation the liquid is removed and reextracted with a new portion of sodium hydroxide solution. The volume of the combined alkaline extracts is estimated. The extract (2ml) and 8ml of water are shaken for lOmin with Sephadex QAE, A-25 ion exchanger (3ml bed volume). After centrifugation, the liquid is discarded and the ion exchanger rinsed with 5ml of distilled water. The water is discarded and the procedure continued as described below. 

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