อันนี้นะคะ 5.1 The nature of enzymes
Enzymes are complex organic molecules present in living cells where they act as catalysts in bringing about chemical changes in substances. With the development of the science of biochemistry has come a fuller understanding of the wide range of enzymes present in living cells and of their modes of action. Without enzymes, there can be no life. Although enzymes are only formed in living cells, many can be separated from the cells and can continue to function in vitro. This unique ability of enzymes to perform their specific chemical transformations in isolation has led to an ever-increasing use of enzymes in industrial and food processes, in bioremediation, and in medicine, and their production is collectively termed 'enzyme technology'.
The activity of an enzyme is due to its catalytic nature. An enzyme carries out its activity without being consumed in the reaction, and the reaction occurs at a very much higher rate when the enzyme is present. Enzymes are highly specific and function only on designated types of compounds the substrates. A minute amount of enzyme can react with a large amount of substrate. The catalytic function of the enzyme is due not only to its primary molecular structure but also to the intricate folding configuration of the whole enzyme molecule. It is this configuration which endows the protein with its specific catalytic function; disturb the configuration by, for example, a change in pH or temperature, and the activity can be lost. For some enzymes there is an obligatory need for additional factors, termed 'co-factors', thatcan be metal ions, nucleotides, etc. Because of their specificity enzymes can differentiate between chemicals with closely related structures and can catalyst reactions over a wide range of temperatures (0-110°C) and in the pH range 2- l4. In industrial applications this can result in high-quality products, fewer by-products and simpler purification procedures-Furthermore, enzymes are non-toxic and biodegradable (an attractive 'green' issue) and can be produced especially from microorganisms in large amounts without the need for special chemical- resistant equipment.
Enzyme technology embraces production, isolation, purification and use in Soluble or immobilized form. Commercially produced enzymes will undoubtedly contribute to the solution of some of the most vital problems with which modern society is confronted, e.g. food production, energy shortage and preservation, and improvement of the environment, together with numerous medical applications. This new technology has its origins in biochemistry but has drawn heavily on microbiology, chemistry and process engineering to achieve the present status of the science. For the future, enzyme technology and genetic engineering will be two very closely related areas of study dealing with the application of genes and their products. Together, these sciences will attempt to exploit creatively the continuous flow of discoveries being made by molecular genetics and enzymologists.
It is estimated that the world market for enzymes is over $2 billion and will double over the next decade. There are now over 400 companies world wide
involved in enzyme production, with European companies dominating(60%) and the USA and Japan with 55%. Bulk enzyme distribution in various
Industries is shown in Table 5.1 and production of specific bulk enzymes is shown in Table 5-2.