Enzymes, Proteins- Biochemistry - Lecture Slides, Slides of Biochemistry

Download Enzymes, Proteins- Biochemistry - Lecture Slides and more Slides Biochemistry in PDF only on Docsity! ENZYMES ENZYMES ARE PROTEINS ENZYMES ARE CATALYSTS Polymers of amino acids Heat-sensitive Absorb light at 280 nm Reaction accelerators Lower energy of activation of reactions Not consumed in the reaction Stabilize the transition state Docsity.com There are two components to a chemical reaction: (1) its kinetic or rate component, and its thermodynamics, or energy component. When we deal with enzymes, we are concerned primarily with the rate component. Do’s and Don’t’s for Enzymes Do 1. Lowers energy of activation of forward and reverse reactions 2. Speeds up the time required to reach equilibrium or completion 3. Stabilizes the Transition State 4. Conducts a specific reaction with no side products Docsity.com HA-HB + B HA + HB-B HA-HB + B HA + HB-B DG Free Energy Reaction Coordinate Free energy of Activation No change in free energy of reaction + + Transition State Docsity.com HA-HB + B HB-B + HA Free energy of activation of forward reaction Reaction Coordinate Free energy of activation of reverse reaction Free energy change of reaction DG DGf DGr DGf DGr Enzymes low the energy of activation of both forward and reverse reactions. They do not affect the overall free energy Docsity.com Multiple Step Reactions (multi-transition States) A + B [A*] A + B A + B D-glucose + CH3OH (open chain) [-D-glucose] Methyl-D-glucoside (hemiacetal) Slow step (Rate-determining) A* (hemiacetal) Two Steps A-B (methyl-D-glucoside) DG Docsity.com TRIVIAL (Oldest) Trypsin Chymotrypsin Pepsin Appearance Old Yellow Enzyme - Otto Warburg Digestive Fluids, Bacteria, Plants Lysozyme Papain Thermolysin Kuhn’s “enzyme” meaning “in yeast” Cathepsin Docsity.com Product is an aldehyde Substrate is alcohol SUBSTRATE - REACTION TYPE 1. Enzymes given “ase” suffix 2. Substrate first, then reaction type Example CH3CH2OH CH3CHO Reaction removes hydrogen atoms ALCOHOL DEHYDROGENASE Docsity.com TOO MANY REACTIONS TYPES PROBLEM: Dehydrogenases Peptidases Proteases Reductases Glycosidases Isomerases Epimerases Deaminases Amylases Lipases Esterases Acyltransferases Synthetases Synthases DNAses RNAses Nucleosidases Docsity.com CH2OH HO-C-H CH2OH Glycerol + ATP CH2OH HO-C-H CH2OPO3 = + ADP Glycerol phosphate 2.0 Transferases 3.0 Hydrolases CH2OH HO-C-H CH2OPO3 = Glycerol phosphate + H2O CH2OH HO-C-H CH2OH Glycerol + HPO4 - (Transfer group to substrate) (Cleave bonds with H2O) Docsity.com 4.0 LYASE (split C-X without water; reverse forms bond without a need for energy ) Split product of the forward or one substrate of the reverse reaction must have a double bond CH2OPO3 C=O HO-C-H H-C-OH H-C-OH CH2OPO3 CH2OPO3 C=O HO-C-H H H-C-OH CH2OPO3 C H O Fructose 1,6 bisphosphate Dihydroxyacetone phosphate Glyceraldehyde-3-phosphate split unite Docsity.com glucose 6-phosphate fructose 6-phosphate OH CH2OH OPO3 CH2OPO3 CH COOH CH2OPO3 CH COOH 3-phosphoglycerate 2-phosphoglycerate O O CH2OPO3 OH HO H H HH H H CH2OH OH HO HO H OH H 5.0 ISOMERASES (change groups around) Docsity.com