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Enzyme basic information and working of enzyme
- 1. Enzyme 1 by DrManoj
- 2. Enzymes C12H22O11 + 12O212CO2 +11H2O • Highly exergonic reaction • Releases free energy • Does it occur in nature? • Enzymes affect the rate of a reaction and not its equilibrium!
- 3. Enzymes: Uses • Digestion:Amylase, Pepsin, trypsin • Building blocks: DNA, RNA polymerase • Diagnosis: Alanine transaminase, Creatine kinase • Industry: Washing powders • Papain: Meat tenderizer • Trypsin: Baby foods
- 6. What are enzymes? Enzymesare biological catalysts They speed up the rate of biological reactions
- 7. Enzymes as catalysts ◼Catalyst- Speeds up chemical reactions in living organisms by decreasing the energy needed to start the reaction ◼(activation energy) Energy Time Without a catalyst With a catalyst
- 8. Enzymes ◼Louis Pasteur: ‘Vitalism’ ◼EduardBuchner: Identified enzymes ◼James Sumner: Crystallized urease ◼JBS Haldane: Mechanism
- 9. Enzyme structure ◼Most enzymes areproteins ◼They have a globular shape ◼A complex 3-D structure Human pancreatic amylase
- 10. Enzymes and proteinstructure
- 11. Enzymes and proteinstructure
- 12. Ribozyme: a “natural”RNA enzyme ◼In the early 1980s, however, research groups led by Sidney Altman and Thomas Cech independently found that RNAs can also act as catalysts for chemical reactions. ◼This class of catalytic RNAs are known as ribozymes, and the finding earned Altman and Cech the 1989 Nobel Prize in Chemistry.
- 13. mRNA splicing: snRNAsas ribozymes
- 14. Enzyme: The activesite ◼ Region of an enzyme comprised of different amino acids where catalysis occurs (determined by the tertiary and quaternary structure of each enzyme) ◼ The shape and the chemical environment inside the active site permits a chemical reaction to proceed more easily
- 15. The substrate ◼ Thesubstrate of an enzyme are the reactants that are activated by the enzyme and converted to product ◼ Enzymes are specific to their substrates ◼ The specificity is determined by the active site ◼ Enzymes themselves do not undergo any major change or get used up during the reaction
- 16. Cofactors ◼An additional non- proteininorganic molecule that is needed by some enzymes to help the reaction ◼Prosthetic groups can be metals (Metalloenzymes) or non-metals Nitrogenase enzyme with cofactors and coenzymes
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- 19. Coenzymes ◼ An organicor metalloorganic molecule bound to the enzyme by weak interactions / hydrogen bonds ◼ Enzymes containing loosely bound metals are called metal- containing enzymes ◼ Many vitamins are coenzymes Nitrogenase enzyme with cofactors and coenzymes
- 20. Coenzymes ▪Most coenzymes carry electronsor small groups ▪Many have modified vitamins in their structure ▪Tightly bound cofactors or coenzymes are called prosthetic groups
- 21. NAD as acoenzyme
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- 23. Enzyme Nomenclature ◼ holoenzyme- a complete, catalytically active enzyme including all co-factors ◼ apoenzyme - the protein portion of a holoenzyme minus the co-factors ◼ isozyme - (or isoenzyme) an enzyme that performs the same or similar function of another enzyme. This generally arises due to similar but different genes encoding these enzymes.
- 24. Enzyme-Substrate Complex Specificity ◼ Forenzyme and substrate to react, surfaces of each must be complementary ◼ Enzyme specificity: the ability of an enzyme to bind only one, or a very few, substrates thereby catalyzing only a single reaction ◼ Urease has a HIGH DEGREE of Specificity
- 25. Classes of EnzymeSpecificity 1. Absolute: enzyme reacts with only one substrate 2. Group: enzyme catalyzes reaction involving any molecules with the same functional group 3. Linkage: enzyme catalyzes the formation or break up of only certain category or type of bond 4. Stereochemical: enzyme recognizes only one of two enantiomers
- 26. Nomenclature and Classification Enzymesare often classified by placing them in categories according to the reactions that they catalyze: 1. Oxidoreductase 2. Transferase 3. Hydrolase 4. Lyase 5. Isomerase 6. Ligase
- 27. Classification of Enzymes ◼Oxidoreductasescatalyze redox reactions ▪ Reductases ▪ Oxidases
- 28. Classification of Enzymes ◼Transferasestransfer a group from one molecule to another ▪ Transaminases catalyze transfer of an amino group ▪ Kinases transfer a phosphate group
- 29. Classification of Enzymes ◼Hydrolasescleave bonds by adding water ▪Phosphatases ▪Peptidases ▪Lipases
- 30. Classification of Enzymes ◼Lyases catalyze removal of groups to form double bonds or the reverse: break double bonds ▪Decarboxylases ▪Synthases
- 31. Classification of Enzymes ◼Isomerasescatalyze intramolecular rearrangements ▪Epimerases ▪Mutases
- 32. Classification of Enzymes ◼Ligasescatalyze catalyze the joining of two large molecules by forming a new chemical bond
- 33. Why EC Numbers?? Backin the 1950s ◼ The number of known enzymes was increasing rapidly ◼ No guiding authority ◼ The same enzymes became known by several different names, and ◼ The same name was sometimes given to different enzymes ◼ Names often conveyed little or no idea of the nature of the reactions catalyzed
- 34. The Situation WasChaotic… ◼Catalase (also known as equilase, caperase, optidase…) ◼ Diaphorase (dehydrogenase) ◼ Zwischenferment (glucose-6- phosphate dehydrogenase)
- 35. Enzyme Commissions ◼The FirstEnzyme Commission: In August 1955 M. Dixon and O. Hoffmann-Ostenhof convinced the president of the International Union of Biochemistry (IUB) to set up an International Enzyme Commission to tackle the problems ◼Enzymes are classified and named by the reactions they catalyze
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Editor's Notes
- #40 IntEnz is a database focussed exclusively on Enzyme Nomenclature.