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Enzyme and coenzyme


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briefly describe enzyme and coenzyme and its role in many orders. Consist of enzyme nomenclature, enzyme part: prosthetic group, metalions, cofactors, and secondary substrate. Describe inhibition action.

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Enzyme and coenzyme

  1. 1. Enzyme and Coenzyme Pramono,H.
  2. 2. What will we learn? • Foreword • Nomenclature • Activation • Inhibition and mechanism of inhibition • Factor that affect enzymes activity
  3. 3. Foreword • Enzyme are proteins (or RNA) with powerful catalytic activity thus called biocatalysator • Synthesized by biological cells and in all organism, they are involved in chemical reactions related to metabolism • Alcoholic, ripening, aging of meat, etc. • Enzymes play a role in food science
  4. 4. Catalysis • Catalyst is substance that increase reaction without consumed by the reaction • Feature of catalyst – Lowers the activation energy needed to start a reaction – Is not used up during the reaction – Is unchanged after a reaction
  5. 5. Reaksi dengan dan tanpa enzim
  6. 6. Nomenclature • Enzyme classified based on type and mechanism of reaction • Old time: based on hydrolysis of covalent bond – Protease, lipase, amylase, etc. • In one substrate can occur other reaction, not only hydrolysis • Now: enzyme classified based on type and mechanism of reaction
  7. 7. IUB nomenclature system • International Union of Biochemistry 1. Reaksi dan enzim yang mengatalisis enzim tersebut membentuk enam kelas, masing-masing mempunyai 4-13 sub kelas 2. Nama enzim terdiri atas dua bagian, nama pertama menunjukkan substrat dan nama kedua yang berakhiran ase menyatakan tipe reaksi yang dikatalisis 3. Informasi tambahan, bila diperlukan untuk menjelaskan reaksi dapat dituliskan dalam tanda kurung di bagian akhir 4. Enzim memiliki EC yang mencirikan tipe reaksi ke dalam reaksi (digit pertama), subkelas (digit kedua), subsubkelas (digit keempat)
  8. 8. Based on EC 1. EC 1 Oksidoreduktase: mengatalisis reaksi oksidasi/reduksi 2. EC 2 Transferase: mentransfer gugus fungsi 3. EC 3 Hidrolase: mengatalisis hidrolisis berbagai ikatan 4. EC 4 Liase: memutuskan berbagai ikatan kimia selain melalui hidrolisis dan oksidasi 5. EC 5 Isomerase: mengatalisis isomerisasi sebuah molekul tunggal 6. EC 6 Ligase: menggabungkan dua molekul dengan ikatan kovalen
  9. 9. Example Alchohol dehidrogenase Substrate Reaction catalyst by enzyme
  10. 10. Mechanism LOCK AND KEY
  11. 11. Enzyme cofactors • Rigorous analysis has demonstrated that numerous enzymes are not pure proteins • They can contain metal ions and/or low molecular weight nonprotein organic molecules • These nonprotein hetero constituents are denoted as cofactor which are indispensable for enzyme activity
  12. 12. Systematics of cofactor-containing enzymes Holo-enzyme Cofactor Apoenzyme Metalions Coenzyme Proeshetic group Cosubstrate Stable binding Cyclic regeneration Involved in reaction
  13. 13. Metalions • Metalions commonly called cofactor • Function: – Stabilizers of enzyme conformation – Direct participation in catalysis • Located in active site • Common metal ions: – Magnesium, calcium and zinc – Iron, Copper, and molybdenum
  14. 14. Hexokinase
  15. 15. Nature review microbiology Nitrogenase
  16. 16. Prosthetic group • Flavin • Hemin • Pyridoxal phosphate
  17. 17. Flavin • Riboflavin known as Vit. B2 is the building block of flavin mononucleotide (FMN) and Flavin adenine dinuleotide (FAD) • Both act as prostetic groups for electron transfer reactions in number of enzymes
  18. 18. Hemin • Peroxidases from food of plant origin and several catalases contain ferri-protoporphyrin IX • Chromophore responsible for the brown color of the enzymes • In catalytic reactions there is a change in the electron excitation spectra of the peroxidases
  19. 19. Peroxidase
  20. 20. Pyridoxal phosphate • Pyridoxal phosphate are designated as vitamin B6 and are essential ingredients of food • Coupled to the enzyme as a prosthetic group through a lysyl residue, involved in conversion reactions of amino acids
  21. 21. Structure of prosthetic group Vit.B6
  22. 22. Role of Vitamin as prosthetic group
  23. 23. Cosubstrate • Consist of NAD and ATP • Nicotinamide adenine dinucleotide (NAD+) – Transhydrogenase (e.g. lactate dehydrogenase, alcohol dehydrogenase) dehydrogenate or hydrogenate their substrates with the help of pyridine cosubstrates – NAD residue accepts or donate a hydride ion (H-)
  24. 24. Theory of Enzyme Catalysis • Active site – Small part of enzyme where reaction of catalysis occurs – Enzyme molecule is often larger in size by a factor of several orders of magnitude – Prove: Glucose oxydase (Mr= 150,000) which glucose (Mr=180)
  25. 25. Substrate binding • Stereospecificity – Before being bound to the binding locus, the substrates are distinguished by their cis-, trans- isomerism and by their optical antipodes • Lock and key hypothesis – E. Fisher • Induced-fit model – The active site can ‘move’ to get correct position before catalysis reaction occurs
  26. 26. Factors that affect enzyme reaction • Temperature • pH • Inhibitors
  27. 27. Temperature • Remind that enzyme is consist of protein? • Denaturation • But every enzyme has it own characteristic, regarding to its sulfide bond (or cystein bond): – Low amount of sulfide bond sensitive to higher temperature • Trypsin  denaturated in 95oC – High amount of sulfide bondTaq Polymerase still active in 95oC
  28. 28. pH • pH affect 3D conformation of enzyme • Different enzyme different optimum pH
  29. 29. Enzyme inhibition • Reversible – Enzyme show it activity after inhibitor released • Irreversible – Total damage
  30. 30. Diisopropyl fluorophosphate (DFP) react with serine protease Reversibel Irreversibel
  31. 31. Reversible inhibition • Competitive inhibition • Uncompetitive inhibition, • Mixed inhibition • Non-competitive inhibition • Feedback inhibition
  32. 32. Competitive inhibition
  33. 33. Feedback inhibition
  34. 34. Thank you @heruiwak