DEAE-dextran preparation

Water-insoluble PEC were prepared by mixing oppositely charged polyelectrolytes, e.g. DEAE dextran with CMD [340,341], sodium dextran sulfate, poly(styrene sulfonate) (NaSS) [342], poly(sodium L-glutamate) (PSLG), poly(vinyl alcohol)sulfate [343], or potassium metaphosphate (MPK) [240]. They are useful as membranes or in biomedical applications [343,344]. 

Methods for the depolymerization of dextran to uniform fractions of lower molecular weight have led to the use of two dextran fractions that are suitable for parenteral administration.13,30 In the United States, a dextran fraction of MW 70,000 is used as a blood-volume expander. Clinical dextran is used to restore blood volume in the treatment of patients who have either lost considerable amounts of blood or are in shock. A dextran fraction of MW 40,000 is used to improve the flow in capillaries, to prevent or treat vascular occlusion, and to perfuse organs artifically. B-512(F) dextran is completely metabolized141 in man when fractions are administered parentally. Various dextran fractions have been used to prepare numerous derivatives,29 such as the sulfates, and 0-(2-diethylaminoethyl) (DEAE)-dextran, and complexes with various metals. Dextran sulfates have anticoagulant,340 antilipemic,340 and anti-ulcer341 activity. A soluble, iron-dextran complex342 of MW 5000 is used to alleviate iron-deficiency anemia, and a calcium complex332 alleviates hypocalcemia of cattle. 

Enzyme activity has a certain dependence on temperature, and the general enzyme has an optimal temperature, and immobilized enzyme is no exception. Compared to the solution enzyme, the optimum temperature of immobilized enzyme shows ups and downs. The study found that the aminoacylase was bound to DEAE-cellulose and DEAE-dextran using ion-binding, or embedded in crosslinked polyacrylamide gel. Thus, the immobihzed enzyme was prepared, and its optimum temperature was somewhat higher than that before the immobilization. When aminoacylase was immobilized by iodine acetyl cellulose with covalent binding, its optimum temperature was somewhat lower than that before the immobilization. When the glucose isomerase was boimd to porous resin with covalent binding. 

A lyophylisate of the expressed sap of . purpurea in cultures of mice L-cells (clone 929) at a concentration of 10 ig/ml to 100 Llg/ml exhibited no direct antiviral activity against encephalomyocarditis virus (EMC virus) or vesicular-stomatitis-virus (VSV). An antiviral effect was only observed when the sap was added together with DEAR dextran. DEAE dextran itself showed no effect. The authors concluded an interferon-like activity [145]. By the colorimetric assay according to Finter and by the Plaque-Reduction-Assay it could be shown, that mice L-929 cells or HeLa cells became resistant for 24 h against influenza-, herpes- and vesicular-stomatitis-virus by 50-80%, when the cells were pretreated 4-6 h with 20 ig/ml of an . purpurea expressed sap preparation. Together with hyaluronidase, no effect was observed. The active component could not be inactivated by heat (60-80 C) [146]. 

Fig. 7. Dose response curves for the effect of polycations on the infectivity of poliovirus single-stranded RNA and RF-RNA. The infectivity of a viral RNA preparation was assayed with suspended cells exposed to various concentrations of polycations. Poly-L-omithine was added 5 minutes prior to the RNA, DEAE-dextran together with the...

The biological activity of standard preparations of RNA was assayed with the agar cell suspension plaque assay. Polycations were added at the concentrations indicated one (a) or five (b) minutes before and/or five minutes after (c) the addition of RNA to the suspended cells. DEAE-dextran was added together with the RNA. 

The utility of the 2-diethylaminoethyl ethers of insoluble polysaccharides is well established in the field of ion-exchange chromatography, and so such compounds as 0-( 2-diethylaminoethyl) cellulose and 0-(2-diethylaminoethyl) cross-linked dextran (DEAE-Sephadex) are common laboratory reagents for fractionations. The preparation, properties, and uses of 0-(2-diethylaminoethyl)-, 0-[2-(triethylammonium)-ethyl]-, and 0-(2-aminoethyl)-cellulose have been reviewed. Modification of the reaction conditions originally employed for diaminoethylation... 

The L-cells did not respond to 10 yg/ml of plain poly I poly C, but those cultures that had DEAE-Dx in addition to the poly I-poly C yielded 300 units of interferon per ml. The mechanism of this enhancement, however, appears to be complex. One can prepare a complex of poly I poly C with DEAE-Dx simply by mixing the two in proper proportions. Such a complex is more resistant to hydrolysis by RNase than is plain poly I-poly C. When this dextran complex is administered to mice it elicits 10 times more serum interferon than does poly I poly C. It is also more effective in L-cells than is the uncomplexed d.s. RNA. 

The commercial availability of these two ion exchangers provided the biochemist with powerful tools for the separation of proteins and nucleic acids under very mild conditions. DEAE-derivatives of agaran have been prepared as a matrix for protein electrophoresis and immunoelectrophoresis. DEAE-derivatives of cross-linked dextran (see section 7.4) have been prepared with the idea of combining ion exchange and molecular sieving of charged macromolecules. 

---