Biocatalysis immobilization

Keywords Biocatalysis Immobilized enzymes Immobilized biocatalyst ... 

Chibata, L, T. Tosa, and T. Sato. 1986. Biocatalysis Immobilized Cells and Enzymes. Journal of Molecular Catalysis 37 (l) l-24. 

Some of the industrial biocatalysts are nitrile hydralase (Nitto Chemicals), which has a productivity of 50 g acrylamide per litre per hour penicillin G amidase (Smith Kline Beechem and others), which has a productivity of 1 - 2 tonnes 6-APA per kg of the immobilized enzyme glucose isomerase (Novo Nordisk, etc.), which has a productivity of 20 tonnes of high fmctose syrup per kg of immobilized enzyme (Cheetham, 1998). Wandrey et al. (2000) have given an account of industrial biocatalysis past, present, and future. It appears that more than 100 different biotransformations are carried out in industry. In the case of isolated enzymes the cost of enzyme is expected to drop due to an efficient production with genetically engineered microorganisms or higher cells. Rozzell (1999) has discussed myths and realities... 

Itoh, N., Nakamura, M., Inoue, K. and Makino, Y. (2007) Continuous production of chiral 1,3-butanediol using immobilized biocatalysts in a packed bed reactor promising biocatalysis method with an asymmetric hydrogen-transfer bioreduction. Applied Microbiology and Biotechnology, 75 (6), 1249-1256. 

Macroporous substrates with interconnected voids can be used as platforms for biomacromolecule separation and enzyme immobilization. These assemblies are likely to find application in biocatalysis and bioassays. The inorganic framework can provide a robust substrate, while their large and abundant pores allow the transportation of biomolecules. The availability of various morphologies for macroporous materials provides another level of control over the function of the hybrids. 

Membranes can be used as a matrix for immobilization of a catalyst. Four basic types of catalysts are relevant (a) enzymes and (b) whole cells for biocatalysis (c) oxides and (d) metals for nonbiological synthesis. Biocatalysts will be considered first since their immobilization in (or on) the membrane was explored much earlier. Five techniques have been studied in varying degrees. They are (1) enzyme contained in the spongy fiber matrix ... 

It was reported that PEGylated lipase entrapped in PVA cryogel could be conveniently used in organic solvent biocatalysis [279], This method for enzyme immobilization is more convenient in comparison to other types of immobilization that take advantage of enzyme covalent linkage to insoluble matrix, since the chemical step which is time consuming and harmful to enzyme activity is avoided. The application of this catalytic system to the hydrolysis of acetoxycoumarins demonstrated the feasibility of proposed method in the hydrolysis products of pharmaceutical interest and to obtain regioselective enrichment of one of the two monodeacetylated derivatives. 

Because enzymes are insoluble in organic solvent, mass-transfer limitations apply as with any heterogeneous catalyst. Water-soluble enzymes (which represent the majority of enzymes currently used in biocatalysis) have hydrophilic surfaces and so tend to form aggregates or stick to reaction vessel walls rather than form the fine dispersions that are required for optimum efficiency. This can be overcome by enzyme immobilization, as discussed in Section 1.5. 

Pharmaceutical production generally uses multipurpose equipment, and so entrapment behind a membrane would require significant capital expenditure on specialized equipment. In spite of this, the use of membrane reactors in biocatalysis represents an efficient method of enzyme immobilization, given the large molecular weight difference between enzymes (10-150 kDa) and most substrates (300-500 Da). The reader is referred to some recent reviews on the topic. 

A. Aoki, M. Ueda, H. Nakajima, and A. Tanaka, Construction of a photo controllable enzyme reaction system by co-immobilization of an enzyme and a semiconductor. Biocatalysis, 2, 89-95 (1989). 

In summary, the synthesis and in situ regeneration of nucleotide sugars by combinatorial biocatalysis suffers from the main disadvantage that each enzyme has to be produced in sufficient amounts. This affords efficient recombinant protein produchon hosts being a bottleneck for some genes [25]. However, once a multi-enzyme system has been developed, the productivity can be improved by repetitive use of the biocatalysts as demonstrated for repetitive batch syntheses with soluble enzymes [25, 38] or with immobilized enzymes [48]. The advantage... 

Barros, R.J., Wehtje, E., Garcia, F.A.P. and Adlercreutz, P (1998) Physical characterization of porous materials and correlation with the activity of immobilized enzyme in organic medium. Biocatalysis and Biotransformation, 16, 67-85. 

Ferreiradias, S. and Dafonseca, M.M.R. (1995) The effect of substrate hydrophobicity on the kinetic-behavior of immobilized Candida rugosa lipase. Biocatalysis and Biotransformation, 13, 99-110. 

Ison, A.P., Dunnill, P., Lilly, M.D., Macrae, A.R. and Smith, C.G. (1990) Enzymatic interesterification of fats Immobilization and immimogold localization of hpase on ion-exchange resins. Biocatalysis, 3, 329-342. 

If biocatalysis is so attractive, why was it not widely used in the past The answer is that only recent advances in biotechnology have made it possible. First, the availability of numerous whole-genome sequences has dramatically increased the number of potentially available enzymes. Second, in vitro evolution has enabled the manipulation of enzymes such that they exhibit the desired properties substrate specificity, activity, stability, and pH profile [42]. Third, recombinant DNA techniques have made it, in principle, possible to produce virtually any enzyme for a commercially acceptable price. Fourth, the cost-effective techniques that have now been developed for the immobilization of enzymes afford improved operational stability and enable their facile recovery and recycling [43]. 

---