Biocatalyst polymeric support

TentaGelS-NH2 was chosen as the polymeric support, i.e. a polystyrene resin equipped with terminally NH2-functionalized oligoethylene glycol units. It has a polar surface and swells in aqueous solutions allowing the biocatalyst access to the polymer matrix [53]. 

Shapiro remained true to his role of critical observer at the ISSOL conference in 2002 in Mexico there he expressed the opinion that the beginnings of life did not involve polymers at all (be they nucleic acids or proteins, or their hypothetical precursors pre-nucleic acids or pre-proteins), but initially involved interactions between monomers, the polymeric biomolecules being formed in later phases of molecular evolution. In this monomer world , reactions were supported by small biocatalysts (Shapiro, 2002). 

This process involves the suspension of the biocatalyst in a monomer solution which is polymerized, and the enzymes are entrapped within the polymer lattice during the crosslinking process. This method differs from the covalent binding that the enzyme itself does not bind to the gel matrix. Due to the size of the biomolecule it will not diffuse out of the polymer network but small substrate or product molecules can transfer across or within it to ensure the continuous transformation. For sensing purposes, the polymer matrix can be formed directly on the surface of the fiber, or polymerized onto a transparent support (for instance, glass) that is then coupled to the fiber. The most popular matrices include polyacrylamide (Figure 5), silicone rubber, poly(vinyl alcohol), starch and polyurethane. 

One of the extensively used synthetic polymers used as a support for immobilization of biocatalysts is polyacrylamide (PAAm) [287,288], The major advantage is that it can be polymerized either chemically or by using radiation. Advantages of y-ray polymerization against chemical polymerization is that the polymerization can be carried out even under frozen conditions thus allowing the matrix to be molded to any form such as beads or membranes [289-291], However one of the major drawbacks of this polymer especially in a membranous form is its brittleness. 

The rapid development of biotechnology during the 1980s provided new opportunities for the application of reaction engineering principles. In biochemical systems, reactions are catalyzed by enzymes. These biocatalysts may be dispersed in an aqueous phase or in a reverse micelle, supported on a polymeric carrier, or contained within whole cells. The reactors used are most often stirred tanks, bubble columns, or hollow fibers. If the kinetics for the enzymatic process is known, then the effects of reaction conditions and mass transfer phenomena can be analyzed quite successfully using classical reactor models. Where living cells are present, the growth of the cell mass as well as the kinetics of the desired reaction must be modeled [16, 17]. 

Candida antarctica Lipase B (CALB) is atfracting increasing attention as a biocatalyst for the synthesis of low molar mass and polymeric molecules. Almost all publications on immobilized CALB use the commercially available catalyst Novozym 435, which consists of CALB physically adsorbed onto a macroporous acrylic polymer resin (Lewatit VP OC 1600, Bayer). Primarily, commercial uses of CALB are limited to production of high-priced specialty chemicals because of the high cost of commercially available CALB preparations Novozym 435 (Novozymes A/S) and Chirazyme (Roche Molecular Biochemicals). Studies to better correlate enzyme activity to support parameters will lead to improved catalysts that have acceptable price-performance characteristics for an expanded range of industrial processes. 

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