Dextran enzyme

Fig. 8 Synthesis of amino acids by a multienzyme system consisting of leucine dehydrogenase (LeuDH) catalyzing the reductive amination of the corresponding keto acid, L-lactate dehydrogenase (l-LDH), and lactate for the regeneration of NADH and urease for the in situ generation of ammonia. The coenzyme NAD+ was covalently bond to dextran, enzymes and dextran-coupled NAD+ were...

Attachment of enzymes to activated insoluble polysaccharides is routinely carried out at pH 9.0, and this pH has been found to be suitable for synthesis of most soluble dextran-enzyme... 

Our present approach in the preparation of new dextran-enzyme conjugates is initially to test the standard conditions. If such conditions do not give satisfactory results, either in terms of retention of activity or extent of conjugation, the effect of the three important parameters, pH, temperature and duration of reaction are then investigated to establish appropriate conditions for coupling. In some cases it has also been found useful to examine the effect of these variables on the stability characteristics and other properties of the resulting dextran-enzyme conjugates. 

For those reactions where the products are larger in molecular weight than the enzyme, one is forced to go to an immobilized enzyme system or to this system where the dextran-enzyme complex can be made larger than the products. 

Aminosalicyclic acid, bacitracin, blood plasma, blood serum, methicillin salts, culture media, dextran, enzymes, gamma-globulin, hormones, streptomycin, iron dextran, lysine, casein hydrolysate, penicillin, serum hydrolysate, penicillin, serum hydrolysate, tetracycline vitamins, oleandomycin, chloramphenicol succinate salts... 

Two-Phase Aqueous Extraction. Liquid—Hquid extraction usually involves an aqueous phase and an organic phase, but systems having two or more aqueous phases can also be formed from solutions of mutually incompatible polymers such as poly(ethylene glycol) (PEG) or dextran. A system having as many as 18 aqueous phases in equiHbrium has been demonstrated (93). Two-phase aqueous extraction, particularly useful in purifying biological species such as proteins (qv) and enzymes, can also be carried out in combination with fermentation (qv) so that the fermentation product is extracted as it is formed (94). 

Biopolymer Extraction. Research interests involving new techniques for separation of biochemicals from fermentation broth and cell culture media have increased as biotechnology has grown. Most separation methods are limited to small-scale appHcations but recendy solvent extraction has been studied as a potential technique for continuous and large-scale production and the use of two-phase aqueous systems has received increasing attention (259). A range of enzymes have favorable partition properties in a system based on a PGE—dextran—salt solution (97) ... 

Homopolysaccharides are synthesised by relatively few spedfic enzymes and are not constructed from subunits. The commerdally important homo polymer dextran is synthesised extracellularly by the enzyme dextransucrase. In Leuconostoc mesenteroides the enzyme is induced by the substrate sucrose. This is deaved to release free fructose and link the glucose to the redudng end of the acceptor dextran chain, which is bound to the enzyme. The product from this bacterium is composed almost exdusively of... 

Extraction for enzyme recovery is a common process. Polyethylene glycol-dextran mixture is used to recover a-amylase from fermentation broth. Given a partition coefficient of 4.2, calculate the maximum enzyme recovery when... 

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