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Nature and Mechanism of Enzymes
- 1. ENZYMES Nature, Classification and Mechanism of action By: Kuljit kaur Lecturer Kanya Maha Vidyalaya Kuljitk03@gmail.com
- 2. Do watch these videos before you continue https://www.youtube.com/watch?v=XTUm-75- PL4 (This one is a fun video) https://www.youtube.com/watch?v=ozdO1mLX BQE
- 3. INTRODUCTION They are the BIO-CATALYST. • Biological in origin and regulate specific function. • Water soluble • Colloidal organic macromolecules. • Wholly or partially proteinaceous. • Produced in microamounts. • Trigger rate of metabolism.. • Not itself changed . • Regenerated . • Does not change equilibrium constant . • Increases rate of reaction.
- 4. • Specific – substrate and condition specific. • Enzymes :1. endoenymes (metabolic enzymes) 2. exoenzymes (digestive enzymes)
- 6. Discovery of enzymes • First reported by W. Kuhne but Edward buchner first isolated it from the yeast cells. • Buchner gave term enzyme : en- in, zyme-yeast • So enzymes means “inside the yeast”.
- 7. IMPORTANCE OF ENZYMES • Metabolic pathway is stepped process and each step is catalysed by enzymes. • A biological reaction needs enzyme for two reasons: 1. metabolic actions occur at controlled temperature. 2. Act as biocatalyst. Absence of enzymes may be fatal.
- 8. CHEMICAL NATURE • Wholly or partially proteinaeous . • Specific 3- dimesnional tertiary structure. • All proteins are not enzymes.
- 9. • The proteinous nature of enzymes is evident from: 1. 2. 3.Enzymes like proteins are macromolecules. 4.Enymes and proteins both do not pass through dialyzing membrane. 5.Both are colloidal in nature. Proteins and enzymes boiled coagulation enzymes hydrolysis Amino acids
- 10. Classification on basis of chemistry Components of compound enzyme: ENZYMES Pure proteinous enzymes Conjugated or compound proteinous enymes A) Apoenzymes B) Co-factor
- 11. Concept of Apoenzyme and Holoenzyme • HOLOENZYME: It is always a conjugated protein. • Apoenzyme: protein part • Cofactor/prosthetic group : non-protein part. APOENZYME COFACTOR Or Prosthetic group HOLOENZYME
- 12. • Before joining cofactor, apoenzyme is inactive and is also called ZYMOGEN or PROENZYME. • Cofactors are not covalently bound but are tightly bound. • Organic prosthetic groups can be covalently bound.
- 13. CATALYST AND ENZYME • Catalyst increases the rate of chemical reactions while enzymes ehances the rate of biochemical reactions. • So the enzymes are BIO-CATALYST. • Similarities :1. Both are effective in very small amount. 2.Both remain unchanged in reaction qualitatively and quantitatively. 3.Have no effect on equilibria; they just speed up the reaction. 4. They lower the value of activation energy.
- 15. S.No. Class Major subclasses 1. Oxidoreductases Dehydrogenases, Oxidases,Reductases,Oxygenases 2. Transferases Transaldolases, Phosphotransferases,Kinases 3. Hydrolases Peptidases,Deaminases 4. Lyases Decarboxylases,Aldolases 5. Isomerases Mutases, isomerases, Racemases 6. Ligases Synthetases , Carboxylases https://www.youtube.com/watch?v=0 Nr9Pc00qOk
- 16. Mechanism of enzyme action • https://www.youtube.com/watch?v=hXeMb- CBTW0 Lock and key mechanism • https://www.youtube.com/watch?v=V8TOWTp71tE Induced fit mechanism
- 18. Nature of active sites in lock and key mechanism • Active sites contain special groups e.g. –OH group ,-NH2,-COOH,-SH
- 21. Michaelis-Menten Hypothesis • The minimum amount of energy required to bring the substrate molecules of one mole in the reactive form, is called activation energy. • https://www.youtube.c om/watch?v=np2JUCVv BwQ
- 22. Factors affecting enzyme activity • Substrate concentration • Temperature • pH • Enzyme concentration https://www.youtube.com/watch?v=ojXUxR0gk AI
- 23. Substrate concentration • First stated in 1913, it assumes the rapid reversible formation of a complex between an enzyme and its substrate (the substance upon which it acts to form a product). It also assumes that the rate of formation of the product, P, is proportional to the concentration of the complex. The velocity of such a reaction is greatest when all the sites at which catalytic activity can take place on the enzyme molecules (active sites) are filled with substrate—i.e., when the substrate concentration is very high.
- 24. Temperature • Temperature plays an important role in biology as a way to regulate reactions. Enzyme activity increases as temperature increases, and in turn increases the rate of the reaction. This also means activity decreases at colder temperatures. All enzymes have a range of temperatures when they are active, but there are certain temperatures where they work optimally. • While higher temperatures do increase the activity of enzymes and the rate of reactions, enzymes are still proteins, and as with all proteins, temperatures above 104 degrees Fahrenheit, 40 degrees Celsius, will start to break them down.
- 25. pH
- 26. Enzyme concentration • In the presence of high substrate concentration, increase in enzyme concentration accelerates the velocity of enzyme-catalysed reactions. • V∝[E] V=K[E] Where is V is velocity of reaction, [E]is enzyme concentration and k is constant.