Enzyme technological aspects

Chemical Aspects of Enzyme Technology—Fundamentals, Plenum Press, New York, 1990. Various eds.. Enzyme Engineeiing, vols. 2-5, Plenum Press, New York, 1974—1980. Wingard, L. B., I. V. Berezin, and A. A. Klyosov (eds.). Enzyme Engineeiing—Future Directions, Plenum Press, 1980. 

Although there are many biocide alternatives available on the market, for example enzyme technology or bio-dispersants, there appears to be a continued requirement for the use of biocides in order to reduce the levels of microbiological contamination entering the paper making process. The increased awareness of environmental and safety aspects will continue to play an important role on the selection of biocides for paper making processes. The use of legislation to select biocides must be done in parallel with each plants internal risk assessment. No one biocide active will meet all the criteria set out by different European countries and hence the use of these actives must be carefully assessed on a plant by plant basis. 

Figure 9.1 shows the tridimensional structure of chloroperoxidase where some potential modification sites are marked. These include side chains of amino acids such as lysine, histidine, and aspartic acid, as well as the propionates from the heme group and carbohydrate moieties. To illustrate how enzyme technology has impacted the development of biocatalysts based on peroxidases, we highlight important aspects described in literature immobilization, chemical and genetic modification of peroxidases. 

Screening for the optimum reaction conditions with whole cells, crude or purified enzymes (including technological aspects such as co-factor regeneration, immobilization, type of reactor, etc.). 

The properties and modes of action of cellulases and technological aspects of the enzymic depolymerization of cellulosic materials have been discussed. 

A recent edition of Enzymes in Food Processing includes contributions both on chemical and technological aspects of the uses of enzymes in food processing. Information on industrial preparations of microbial enzymes and the applications of enzymes in the Food Industry are accorded particular attention. Carbo-... 

Here we will focus on the biochemical aspects. The techniques of isolating enzymes, the process of enzyme immobilisation and the behaviour of immobilised enzyme reactors are discussed in detail in the BIOTOL text Technological Applications of Biocatalysts", so will not deal with these aspects in detail here. In outline, however, once the desired enzyme is isolated, it is attached to a carrier material. In order to ascertain sufficient accessibility of the enzyme, a bifunctional spacer molecule is attached to the carrier ... 

The works presented in Tables 1.1 to 1.3 [76-86,109-122] deal only with theoretical aspects of the enzymic biochemical devices, and the biochemical devices were not carried into practice. Moreover, Okamoto [85] suggests using silicon technology instead of biomaterials for practical implementation of the device based on the cyclic enzyme system. 

S. Guzy, Enzymic reactors for biomedical uses engineering aspects, D.Sc. thesis, Technion (Israel Institute of Technology), Haifa, Israel, 1989. 

The recent literature in bioelectrochemical technology, covering primarily the electrochemical aspects of enzyme immobilization and mediation, includes few reports describing engineering aspects of enzymatic biofuel cells or related devices. Current engineering efforts address issues of catalytic rate and stability by seeking improved kinetic and thermodynamic properties in modified enzymes or synthesized enzyme mimics. Equally important is the development of materials and electrode structures that fully maximize the reaction rates of known biocatalysts within a stable environment. Ultimately, the performance of biocatalysts can be assessed only by their implementation in practical devices. 

The second aspect refers to the protein nature of enzymes. In 1894 Fischer (Fischer, 1909) stated that amongst the agents which serve the living cell the proteins are the most important. He was convinced that enzymes are proteins. The role of this key problem may be illustrated with a citation from Fruton (1979) ... the peptide theory was indeed only a hypothesis fifty years after Franz Hofmeister and Emil Fischer advanced it... (in 1902). The nature and stracture of proteins remained unknown throughout the 19th century remarkably, technological applications were nevertheless put into practice since the middle of the century (see above), based on their action, eventually recognized as catalysis, only. 

Immobilized enzymes based on the adsorption may obtain high activities. Another interesting aspect of the technology is that the so-called on column loading (OCL) process is possible. At the beginning the ion exchange resin is only partly loaded with... 

This chapter is not only an update of our review of 1997 [1] but also an overview of the latest development in enzyme-based flavour technology. Some aspects of the present chapter are based on the previous review [1]. 

The book assumes a knowledge of chemistry and biochemistry but not of dairy chemistry. As the title suggests, the book has a stronger biochemical orientation than either Principles of Dairy Chemistry or Dairy Chemistry and Physics. In addition to a fairly in-depth treatment of the chemistry of the principal constituents of milk, i.e. water, lactose, lipids, proteins (including enzymes), salts and vitamins, various more applied aspects are also covered, e.g. heat-induced changes, cheese, protein-rich products and the applications of enzymes in dairy technology. The principal physical properties are also described. 

---