Dextran dextranase

Control. Factory control is based on temperature, pH, and polarization. Cane is tested by various means as it comes to the mill to determine its characteristics and to determine the amount to pay the farmer. Control of microbial infection, discussed above, is important. The starch content of juice from immature cane can be significant (e.g., in Louisiana and South Africa), and amylase enzyme may be added continuously to the clarified juice to reduce it. Starch will cause severe viscosity problems if not removed. If there is a problem with dextran, dextranase enzyme can be added, but it is expensive and not as effective as desired.40... 

Figure 7.3874 shows how transmembrane pressure can affect molecular weight distribution in the permeate for the system dextran-dextranase when enzymes are bound to polysulfone flat membranes by means of glutaraldehyde. 

Dextran dextranase -f a-glucosidase-f glucose oxidase raw sugar... 

A dextran-dextranase system has been used to examine the synergistic effect of exo- and cndo-enzymes acting jointly on polymeric substrates. An endo-dextranase (from Penicillium funiculosum) and an cxo-dextranase (from Streptococcus mitis) produced D-glucose more rapidly from dextrans than the summed effects of the individual enzymes. 

Fig. 20. Structured flows developed between the bottom solution containing dextran with 6.146 x 10-2 g/g phosphate buffer at pH 6.0 and dextranase with 10 units/g phosphate buffer (= 2.63 x 10s g/g phosphate buffer) and the top solution containing dextran with 3.952 x 10-2 g/g phosphate buffer (including blue dextran). The boundary was formed 3 min after the dextranase was added to the dextran solution. The photo was taken 30 min after formation of the initial boundary531...

Comparison270 of the action of a dextranase from Penicilliumfuniculosum on a synthetic a-D-(l—>6)-linked polyglucoseu 22,(b) and a natural dextran... 

D. Abbott and H. Weigel, Studies on dextrans and dextranases. Part V. Synthesis of the three carboxylic acids derived from methyl /1-maltoside, J. Chem. Soc., (1965) 5157-5162. 

Dextran is a physiologically harmless biopolymer because of its biocompatible, biodegradable, non-immunogenic and non-antigenic properties [54, 55]. It can be depolymerised by different a-l-glycosidases (dextranases) occurring in liver, spleen, kidney and lower part of the gastrointestinal tract. 

One argument for the selection of dextran as a drug carrier has often been its susceptibility to degradation. However chemical modification of the polymer may impair the biodegradability. Therefore we have studied the biodegradation of dextran and a number of dextran derivatives by dextranase. For this study model derivatives were prepared using the activation procedures discussed before. 

Reduced dextran dialdehydes. The reaction of dextran (D-OH) with sodium metaperiodate is a two step reaction leading to different kinds of aldehyde functions. Although the aldehyde content can not be precisely predicted from the amount of periodate added, by approximation 1.5 equivalents of periodate are required per dialdehyde structure. By varying the amount of periodate added to the polysaccharide dextran dialdehydes with variable degree of oxidation were obtained. In order to avoid interaction of the polyaldehyde (D-CH=0) with the dextranases the aldehyde groups were subsequently reduced by reaction with sodium borohydride ... 

The dextran derivatives were incubated with dextranase (from Sigma Chem Comp., Grade I product) in a citrate buffer pH=6 at 37°C. The degradation of the polymer was monitored by means of gel permeation chromatography on an analytical Sephadex G-25 column. For comparison degradation of unmodified dextran was carried out as well. In order to differentiate hydrolytic from dextranase-induced processes the degradation was also investigated in absence of enzymes. 

Figure 6. GPC chromatograms of dextran T-70 and a 10% oxidized and subsequently reduced derivative after incubation at pH 6 with and without dextranase.

Figure 8. Enzymatic degradation of dextran and carbamate derivatives of dextran by dextranase. Degree of modification (%) ...

Figure 9. Enzymatic degradation of different dextran derivatives by dextranase. (A) 5% ox.red.Dextran, ( ) 3% succinoylated dextran, (O) 4.5% carbamoylated dextran.

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.

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