Enzymes from extremophiles

Enzymes for Extreme Conditions. The possibihty of using enzymes from extremophiles, which thrive in oil wells, hot temperatures, freezing conditions, etc, is being explored for the removal of environmental contaminants and survival at extreme temperatures (see Wastes, HAZARDOUS WASTE TREATlffiNT BlORETffiDIATION (SuPPLET NT)). 

Butler, L.G., Enzymes in non-aqueous solvents. Enzyme Microb. Technol., 1979,1, 253-259. Gerard A. Sellek, G.A. and Chaudhuri, J.B., Biocatalysis in organic media using enzymes from extremophiles. Enzyme Microb. Technol., 1999, 25, 471-482. 

Enzymes from extremophiles, such as thermozymes, have potential either as products themselves, or as catalysts, or they may be used as sources of ideas to modify mesophile-derived enzymes. Most of the thermozymes maintain their thermoresistant properties when expressed in a mesophilic organism such as... 

One goal of current research is to obtain useful enzymes from extremophiles, the microbes that function in these extreme environments. The process used by one company to obtain commercially useful enzymes consists of the following steps ... 

There are many existing and potential industrial applications of extremophilic enzymes (see Table 2), which take advantage of their capacity to thrive in harsh conditions, relative to their mesophilic (ie, function under moderate conditions) counterparts. For example, the detergent industry makes extensive use of alkaline-stable proteases, accounting for approximately 30% of global enzyme production (27). Enzymes from extremophiles have been used for bioremediation heavy metals and radionuclides from wastewaters (28), as well as for biodegrading hydrocarbons in polar soils (29). It is likely that extremophilic enzymes will find wide use in applications that strategically use their intrinsic robustness as biocatalysts. 

The reaction temperature is around room temperature, although some enzymes from extremophiles, microorganisms from extreme environmental conditions, can react very effectively at temperatures up to 120°C and down to -50°C. Sometimes, enantioselectivity can be improved by a decrease or increase in the reaction temperature. 

Demirjian, D. C., Moris-Varas, F. Cassidy, C. S. (2001). Enzymes from extremophiles. Curr Opin Chem Biol, 5(2), 144-51. 

Proteins from extremophilic organisms, particularly thermophiles, have been the subject of intensive research in recent years. This work has been the subject of numerous reviews (Jaenicke and Bohm, 1998 Russel and Taylor, 1995 Vogt and Argos, 1997 Gerday et al., 1997 Somero, 1995), and we will make no attempt at an in-depth summary. We will confine ourselves to briefly stating the major trends identified thus far. Explaining these trends becomes complicated because the many weak interactions that determine enzyme stability and activity have complex temperature dependencies (see Section II). And evolution injects considerable confusion beyond the laws of physical chemistry. 

A quite interesting area with considerable application potential opens up with enzymes obtained from extremophiles [89]. First reports on properties and functions described a novel a-glucosidase from the acidophilic archaeon Ferroplasma acidiphilium strain Y [90] and two /3-glucosidases from a thermo-tolerant yeast Pichia etchellsii [91]. 

Biomolecules such as enzymes isolated from extremophiles can be highly useful in the food industry due to their unique activities under abnormal conditions, and it has been widely accepted that extremophiles have strong potential to be valuable resources for use in biotechnology (Fujiwara, 2002 Guezennec, 2002 Herbert, 1992). Additionally, the discovery of deep-sea... 

These extremophiles are not typical of the life forms that make up the majority normally encountered by biological engineers. But, they serve as a raninder that life can exist in very harsh conditions, and that there are organisms with competitive advantage to inhabit very unlikely spots. In fact, it is an enzyme from one of these extranophiles Thermus aquaticus, living in the hot springs of Yellowstone National Park in the United States) that is used in the polymerase chain reaction (PGR) to amplify the small samples of DNA (see Section 5.3.4). 

The enzymes produced by these extremophiles, known as extremozymes, can function under extreme conditions. An illustrative list along with an indication of the extreme environments in which they can function is included in Table 20.1 (sources Kushner, 1978 Jones et al., 1983 Huber et al., 1989 Li et al., 1993 Davail et al., 1994 Adams et al., 1995). Enzymes extracted from these microorganisms have been tested for a variety of reactions and optimum temperatures have been found. Examples are enzymes from Pyrococcus furiosus for a- and p glucosidase, a-amylase, protease, and hydrogenase activities (Bryant and Adams, 1989 Costantino et al., 1990 Blumentals et al., 1990 Kegen et al., 1993 Laderman et al., 1993). 

Screening stable enzymes from microorganisms (extremophiles)... 

Lee, C.C., Kibblewhite-Acdnelli, R.E., Wagschal, K., Robertson, G.H., Wong, D.W.S., 2006. Cloning and characterization of a cold-active xylanase enzyme from an environmental DNA library. Extremophiles 10 (4), 295-300. 

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