Enzymology- introduction and classification
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This document discusses enzymes, including their history, classification, and functions. It begins by explaining why enzymes are essential for life, as they allow chemical reactions to occur efficiently. The first discovery of enzymes was in the 1700s during meat digestion research. Key milestones in enzyme research are highlighted, such as the discovery that enzymes are proteins. Enzymes are classified into six major categories based on their catalytic activity. The categories are oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases. Each category is defined by the type of reaction it catalyzes. The document emphasizes that enzymes are essential catalysts that allow life to be maintained by speeding up metabolic reactions.
Enzymology- introduction and classification
- 1. ENZYMES Prof. Dr. V.P. Ach
- 3. What shall we learn? • Why should we learn about enzymes? • Why medicos should know about them? • Who thought about them first?- History • How do we define them? • How do we name them?- The classification
- 4. Why enzymes??? Two Fundamental Conditions for Life : (1) able to self-replicate (2) able to catalyze chemical reaction efficiently and selectively Example : a bag of sugar can be stored for years, but it releases its chemical energy in seconds in human body …… “ catalysis” Life depends on well-orchestrated series of chemical reactions : E. coli has 4288 proteins, 2656 of which are characterized, and 64% (1701) of the characterized ones code enzymes
- 5. Chemical reactions are far slow to maintain life Living system has designed catalysts to fasten the specific reactions Breakdown of nutrients to supply energy Assembly of building blocks Diagnostic importance- diagnosis & prognosis
- 6. Most of the history of Biochemistry is enzyme research • 1700- Meat digestion by stomach • 1800- Conversion of starch to glucose by saliva • 1850 Louis Pasteur .. Fermentation ( sugar → alcohol)- said ferments are inseparable- Theory of ‘Vitalism’ • 1897 Edward Buchner …… yeast extract → enzyme ‘zymase’ (Sucrose → Alcohol) • Willey Kunhe.. Coined ‘Enzyme’ • 1926 James Sumner … Urease crystallization → protein- theory of vitalism rejected • J.B.S. Haldane …… enzyme-substrate interaction
- 10. Milestones in enzyme study • Koshland (1958)- “Induced fit” model was proposed, • Monod (1965)- “Allosteric model” of enzyme was proposed, • 1969- the first chemical synthesis of an enzyme was reported, proving an enzyme is a protein • Mechanisms of thousands enzymes have been studied by X-ray crystallography and NMR • DNA recombinant methods were used to overproduce enzymes and to pinpoint the important amino acids • 2004, the first computer designed enzyme was reported
- 11. What are Enzymes? Enzyme Greek for “in yeast”
- 12. Definition Enzymes are “Biocatalysts”, synthesized by living cells and highly specific in their action. They are: Mostly proteins (Exception- Ribozymes) Heat labile Soluble in water Colloidal Precipitated by precipitation reaction Contain 16% weight as nitrogen
- 13. Classification & Nomenclature A. Recommended name B. Systematic name IUBMB Unambiguous & Informative But Cumbersome 6 major classes Class.Subclass.sub-subclass.substrate
- 15. OTHLIL Oxidoreductases→ Transfer of H, O or e- Transferases → Transfer of gr other than H Hydrolases → Cleave bond & add H2O Lyases → Cleave bond without adding H2O Isomerases → Intramolecular transfers Ligases → ATP dependent condensation of 2 molecules
- 16. 1. Oxidoreductases AH2 + B →A + BH2 Alcohol+ NAD+ ADH Aldehyde + NADH +H+ • Dehydrogenases (hydride transfer) • Oxidases (electron transfer to molecular oxygen) • Oxygenases (oxygen transfer from molecular oxygen) • Peroxidases (electron transfer to peroxide).
- 17. 2. Transferases A-R + B → A + B-R • transfer of an atom or group of atoms (e.g. acyl-, alkyl- and glycosyl- ), between two molecules, but excluding such transfers as are classified in the other groups (e.g. Oxidoreductases and Hydrolases). • Ex- Aminotransferases, all kinases, transmethylases • Hexose + ATP Hexokinase Hexose-6-P + ADP
- 18. 3. Hydrolases Cleavage of ester, ether, peptide or glycosidic bond by addition of H2O Ach + H2O acetylcholine esterase Choline + Acetate Ex: All digestive enzymes, lipase, pepsin, Trypsin, ALP, Urease
- 19. 4. Lyases Cleave bond without addition of H2O Fructose-1,6-BP Aldolase Glyceraldehyde-3-P + Dihydroxyacetone P Ex: Fumarase, Histidase, HMG CoA lyase
- 20. 5. Isomerases Can produce optical, geometrical or positional isomers of substrates Gly-3-P Triose P isomerase DHAP Ex: Racemase, Epimerase
- 21. 6. Ligases (synthetases) ATP dependent condensation of two molecules Acetyl CoA + CO2 + ATP Acetyl CoA Carboxylase Malonyl CoA + ADP + Pi Synthases and synthetases are different !!! Ex: Glycogen synthase, ALA synthase
- 22. We are what we repeatedly do; Excellence is then not an act but a
- 23. For more Medical Biochemistry ppt please visit www.vpacharya.com