ENZYMES IN ORGANIC SOLVENT & their properties.pptx

Enzymes inorganic solvent their properties and reaction and application in different fields.

1. ENZYMES IN ORGANIC SOLVENT Presented by TIASHA CHAKRABORTY 02016001322

2. INTRODUCTION Enzymatic catalysis in organic solvents is a new and rapidly growing area of enzymology. The first report on catalytic activity of chymotrypsin and xanthine oxidase suspended in non aqueous media appeared twenty years ago. It has been a common belief that enzymes are not catalytically active in organic solvents.

3. PROPERTIES Substrate Specificity - W hen the medium is substituted by an organic solvent the enzyme-substrate binding changes affecting both substrate specificity and activity of the catalysts. Example - chymotrypsin Stereo specificity - E nzymes placed in organic solvents retain their stereo selectivity and can be used successfully for preparative synthesis. The transition from water to an organic solvent as the reaction medium, the enantioselectivity of some enzymes changes . Example – Lipase catalysed esterifications

4. Structure - E nzymes in some organic solvents exhibit activities comparable to those in water. This indicates that their structure in these solvents is not radically different from that in water. Example - Protease from Lysobacter enzymogenes suspended in anhydrous acetone and octane was preserved, indicating that the enzyme remains intact in these solvents. Thermo stability - The use of dry organic solvents as a reaction media that significantly increases enzyme stability and their thermostability . Example - stability of porcine pancreatic lipase

5. APPLICATION Alcohol Dehydrogenase Alcohol dehydrogenases are widely used in the preparative production of optically active alcohols and ketones. The instability of dehydrogenases in aqueous environments limit their use for large-scale synthesis. The use of organic solvents as media for alcohol dehydrogenase-catalyzed reactions helps eliminate the problem.

6. Polyphenol Oxidase Attempts to use polyphenol oxidase as a practical catalyst have not been successful due to its instability. Polyphenol oxidase immobilized on glass beads providing a larger surface area, placed in chloroform, and used as a catalyst for oxidation of a number of phenols. The substrate specificity of the enzyme in chloroform was found to be similar to that in water.

7. Horseradish Peroxidase Horseradish peroxidase efficiently catalyzes a variety of oxidations in a number of different organic solvents. The rate of oxidation of p- anisidine with hydrogen peroxide in toluene, ether, and ethyl acetate is as high as 20 % of that observed in aqueous solutions. Due to its high activity and stability in non aqueous media, it was found useful in a variety of applications. For example, it was used for the quantitative analysis of cholesterol in toluene, variety of polymers have been produced.

8. Lipases modification Lipases are used in a variety of esterification reactions for the production of triglycerides with the desired physical properties. The major advantage is the product has more defined chemical composition than that obtained by traditional chemical processes. The lipase is catalytically active in a variety of organic solvents including benzene, hexane, methylene chloride and chloroform. Porcine pancreatic and Candida cylindracea lipases efficiently catalyze esterification of bromopropionic acid with butanol .

9. Steroids, Sugars, and Sugar-Related Compounds The enzymatically produced sugar alcohol esters were found to be far superior to their chemically produced counterparts. Sugars are reasonably well soluble in only few very hydrophilic organic solvents such as pyridine, formamide , and dimethylformamide , i.e., solvents which are the least appropriate for lipases.

10. CONCLUSION It has been demonstrated in recent years that a variety of enzymes are catalytically active in organic solvents. Due to the low water activity, enzymes are highly thermo stable in dry organic solvents and can be used for months without loss of activity. Similar to their action in aqueous solutions, enzymes in organic solvents are substrate-specific.

11. BIBLIOGRAPHY Biocatalysts for Industry -- Jonathan S_ Dordick ( auth _), Jonathan S_ Dordick ( eds _) -- 1, 1991 -- Springer -- 10_1007_978-1-4757-4597-9 -- 530f40822e238004d60529e3118ca99b -- Anna’s Archive.pdf