Extremozymes, Biocatalysis, Ecosystems, Extremophiles, Extremely Psychophilic Enzymes, Bacillus, Extremely Halophilic Enzymes

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Your Ad Here	Extremozymes The use of biocatalysis in chemical reactions is generally restricted to mild conditions of pH, temperature, pressure and aquatic medium. However, enzymes isolated from different living organisms inhabiting ecosystems with extreme conditions of pH, temperature, pressure and solvent, are not constrained with these mild conditions needed for majority of enzymes. These enzymes, therefore, provide information to improve stability, activity and specificity of many enzymes used for industrial biocatalysis. It is now known that enzymes can function at temperatures as high as 140°C and as low as below freezing point. Organisms living in these conditions are described as extremophiles and the enzymes that function under these conditions are therefore described as extremozymes. Most of these extremophiles belong to archaea group of bacteria.
Extremozymes are broadly classified as follows: (i) Extremely psychophilic enzymes, which function at temperatures approaching the freezing point of water; for instance, subtilisin S41 from the psychophile Bacillus S41 differs from other subtilisins in several respects, suggesting structural differences between these psychophilic enzymes and those extracted from mesophiles. (ii) Extremely halophilic enzymes function better in salt solutions. For instance, aspartate aminotransferase from Haloferas mediterranes is inactivated rapidly at room temperature in low salt solutions, but does not denature even at 78.5°C in 3.3M KCI suggesting that the enzyme is more stable in higher salt concentration. A protease from Halobacterium halobium is also similarly affected. (iii) Extremely thermophilic enzymes function at high temperatures and several examples of these enzymes are available now. (DNA polymerase from Thermus aquaticus and Pyrococcus furiosus used for PCR provide one such example). (iv) Extremely barophilic enzymes have been isolated from microbes living in deep sea which are both barophils and psychophiles.
A number of genes encoding extremozymes (e.g. ferredoxin, DNA polymerase, amylase, dehydrogenase, etc.) have been isolated from thermophilic archaea (P. furiosus, P. woesii and Thermococcus littoralis), cloned and expressed in E. coli. Three dimensional structures of some extremozymes have provided opportunities to provide or design more stable versions of enzymes, that can function in extreme salinity, pH, temperatures and non-aqueous media. Selectivity of extremozymes (enantioselectivity, regioselectivity and chemoselectivity) can also be adjusted through judicious use of particular enzymes in organic solvents or water/solvent mixtures.	Your Ad Here

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