Dextran trypsin

Protein isolation with affinity precipitation has been discussed in detail by Mattiasson and co-workers (see, e.g. Galaev and Mattiassion, 1997) and they have provided an exhaustive tabulation. Polymers varied from alginate.s/chitosan to dextran to NIPAM. Examples of the used proteins are from trypsin, p-glucosidase, xylanase, alkaline protease, etc. It is remarkable that affinity precipitation can sometimes give results comparable to affinity chromatography. 

There is currently little understanding of the influence of interfacial composition and (nano)structure on the kinetics of enzymatic hydrolysis of biopolymers and lipids. However, a few preliminary studies are beginning to emerge (McClements et al., 2008 Dickinson, 2008). Thus, for example, Jourdain et al. (2009) have shown recently that, in a mixed5 sodium caseinate + dextran sulfate system, the measured interfacial viscosity increased from qs = 220 mN s m 1 without enzyme to qs = 950 mN s m 1 with trypsin present. At the same time, the interfacial elasticity was initially slightly reduced from (7S = 1.6 mN m 1 to (h = 0.7 mN m, although it later returned to close to its original value. Conversely, in the... 

Waters Q-8HR (strong anion exchange, 8 (jl particles) and DEAE-8HR(weak anion exchange, 8 fi particles) Pentosan polysulfate, dextran sulfate /3-lactoglobulins A and B, a-lactalbumin, soybean trypsin inhibitor (STI) 38... 

Figure 2. Autolysis of trypsin (0) and trypsin-dextran conjugate (O) at pH 8.1...

In addition to showing improved stability in the presence of protein denaturants, we have also found dextran-conjugated enzymes to show improved activity in the presence of such agents. For example, in the absence of calcium, native trypsin is inactive in 8M urea under the same conditions the modified enzyme displays 50% of the activity measured in the absence of urea (11). 

Figure 4. Inactivation of trypsin (0) and trypsin-dextran conjugate (O) at 37°C and pH 8.1 in 8M urea and 5mM 2-mercaptoethanol. The broken line shows the rate of inactivation of trypsin-dextran conjugate after dextranase treatment.

Inhibition of Native Trypsin and Trypsin-Dextran Conjugate by Protease Inhibitors41... 

Many enzymes are known to bind to glass, especially when in dilute solution. Common examples of enzymes that demonstrate this phenomenon are e-amylase (12), trypsin (18), ribonuclease (19) and catalase (20). Conjugation of these enzymes with dextran... 

Figure 6. Sepharose 4B chromatography of trypsin-dextran conjugate (A). The sample contained approximately 145 mg dextran and 14 mg of trypsin. Chromatography of a mixture containing corresponding amounts of dextran and trypsin...

Several processes in the immune response are affected by lithium in vivo and in vitro 139). The proliferative responses of hamster lymphoid cells to concanavalin A or phytohemagglutinin, which stimulate mitosis in T cells, were enhanced by lithium in a serum-free culture system. Proliferative stimulation also was obtained with lithium using the B cell mitogen lipopolysaccharide, but the B cell mitogens dextran sulfate and trypsin had no effect 140-143). Lithium increased the effects of suboptimal concentrations of stimulants, but had smaller effects on stimulation by optimal concentrations. With concanavalin A, the response to optimal stimulatory concentrations was inhibited 140). Paradoxical results such as these may be due to inhibitory effects of lithium on adenylate cyclase, or to effects on membrane transport systems 141). Most of these experiments used very high concentrations of lithium, considerably in excess of normal therapeutic doses (maximal inhibitory concentrations were 10 mM with hamster cells and 5 mM with human lymphocytes). At therapeutic levels of lithium, increased incorporation of [ H]thymidine was seen in human peripheral blood mononuclear cells. 

Assay medium, DCCM-1 (defined cell culture medium—Biological Industries) supplemented with glutamine, penicillin, streptomycin, 0.001% DEAE Dextran, TPCK-treated trypsin, and 0.5% indubiose agarose. 

Takakura Y et al (1989) Control of pharmaceutical properties of soybean trypsin inhibitor by conjugation with dextran. II Biopharmaceutical and pharmacological properties. J Pharm Sci 78 219-222... 

The absorption-enhancing effects of protease inhibitors on the intestinal absorption of water-soluble compounds in rats was also examined. Some protease inhibitors may have absorption-enhancing activities in addition to their protease inhibitory actions (e.g., NaGC) [43, 44]. Aprotinin, bacitracin, and soybean trypsin inhibitor (STI) were used as protease inhibitors, while phenol red and fluorescein isothiocyanate (FITC)-labeled dextran with an average molecular weight of 4000 Da (FD-4) were selected as poorly absorbable and stable model compounds. Bacitracin enhanced the absorption of phenol red from the rat small and large intestine in the presence of the protease inhibitors, and similar results were noted for the intestinal absorption of FD-4 co-administered with bacitracin. Thus, bacitracin was seen to have not only a proteolytic inhibitory action but also an absorption-enhancing capability. 

After immobihzation, the resistance toward protease increases. The reason may be an increase of steric access hindrance to the immobilized protease due to the three-dimensional obstacles of the carrier. If we take aminoacylase for example, under the action of trypsin, the activity of the solution enzyme was only 23%, the activity of the enzyme immobilized by DEAE-cellulose was 33% and the activity of the enzyme immobilized by DEAE-dextran was 87%. Under the action of protease, Pronase P, the activity of the solution enzyme, the enzyme immobilized by DEAE-ceUulose and the enzyme immobilized by DEAE-dextran was 48%, 53%, 88%, respectively. Immobilized protease can generally avoid digestion damaging itself. 

Dextran cyclic imidocarbonate has been used to prepare soluble conjugates of a-amylase from Bacillus amyloliquefaciens and of bovine liver catalase for use in experimental enzyme therapy. The results suggest that by coupling the enzymes with a poorly antigenic macromolecule (dextran) anaphylactic reaction in animals pre-immunized with dextran may be suppressed or eliminated. Trypsin has been immobilized by reaction with dextran cyclic imidocarbonate. 

Kobayashi, M. and Takatsu, K., Cross-linked stabilization of trypsin with dextran-dialdehyde, Biosci. Biotech. Biochem., 58 275-278, 1994. 

Carbonated cross-linked dextrans have been used for the covalent immobilization of trypsin. ... 

Dextran cyclic imidocarbonate derivatives have been prepared and used to immobilize phloretin, fetuin, and co-enzyme A. The co-enzyme was immobilized both by reaction with dextran cyclic imidocarbonate, and also via carbodi-imide-mediated coupling to 6-aminohexanoyl-dextran. y-Irradiation of dextran in the presence of trypsin, pepsin, or ribonuclease leads to production of active immobilized forms of these enzymes. ... 

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