Ch12 enzymes can be taught
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This document provides an introduction to enzymes, including how they catalyze biological reactions with higher rates, milder conditions, greater specificity, and capacity for regulation compared to non-enzymatic reactions. It discusses enzyme-substrate interactions, including the lock and key and induced fit models of binding. It also describes different types of enzyme cofactors and classifications of enzymes based on the type of reaction catalyzed. Examples are given to illustrate the structural specificity and stereochemical specificity of some enzymatic reactions.
Ch12 enzymes can be taught
- 1. Introduction to Enzymes (Chapter 12) Department of Biochemistry and Molecular Biology LSUMC Shreveport, La
- 2. Enzymatic Catalysis Suited to Biological systems Higher reactions rates Milder reaction conditions Greater reaction specificity Capacity for regulation
- 3. Enzyme-substrate interactions-a prerequisite for catalysis Forces Important for substrate recognition Active Site Characteristics
- 4. Models for Enzyme Substrate Interactions LOCK AND KEY INDUCED FIT
- 5. Carboxypeptidase A-Substrate Induced Changes in Active Site Conformation
- 6. Enzyme Cofactors N N N H 2 O O O O N N CH H 2 H H H O P O O O P O O O P O O - - - - ATP
- 7. Enzyme Cofactors + - + N O CH H 2 O H O O H H O P O - N N N H 2 O O O O N N CH H 2 H H H P O O - O O C-NH 2 H + N O CH H 2 O H O O H H O P O - N N N H 2 O O O O N N CH H 2 H H H P O O - O O C-NH 2 H H + H + 2e - - H - 2e .. + NAD NADH
- 8. HS-CH -CH -N-C-CH -CH -N-C-C-C-CH-N N N H 2 O O O O N N CH H 2 H H H O P O - O P O O 2 2 O H H CoASH O - 2 O O H CH 3 CH 3 2 H 2 Enzyme Cofactors
- 9. Enzyme Classifications Oxido-reductases + + CH -CH -OH + NAD CH -CH=O + NADH + H 3 2 3 ALCOHOL DEHYDROGENASE Transferases ++ O O Mg ATP + + ADP HEXOKINASE O CH OH 2 OH OH HO O - O O CH O 2 P - OH OH H HO OH
- 10. Enzyme Classifications Hydrolases PROTEASE O O R-NH -CH-C-NH-CH-C-NH-R R R 1 2 + H O 2 R-NH-CH-C-OH R 1 O NH -CH-C-NH-R 2 R 2 O + Lyases - O ENOLASE O O P O - - CH -OH O-C-H C-O O O O P - - C-O O 2 - CH O-C + H O 2 2
- 11. Enzyme Classifications Isomerases O C-O O-C-H - O CH -O TRIOSE PHOSPHATE ISOMERASE Ligases O - O P O - CH -OH 2 C-O - 2 O P O O - - HO-C-H O O CH -C-OH + CoASH + ATP ACETYL CoA SYNTHETASE 3 CH -C-S-CoA + AMP + PPi 3
- 12. Enzymatic Reactions of High Structural Specificity H N-C-NH-(CH ) -CH-C-0-CH -CH H N-C-NH-(CH ) -CH-C-O 2 NH 2 2 3 2 3 2 O NH NH 2 C O 2 3 O - NH C O + + TRYPSIN FAST (1000x) HCH-C-0-CH -CH O 2 3 TRYPSIN SLOW HCH-C-0 O - NH C O NH C O Hydrolysis
- 13. Enzymatic Reactions of High Structural Specificity HOH C O CH OH HO O O O Isomerization - P O 2 2 - O - O O O O CH OH 2 P - OH OH HO O-O O O CH O 2 P - OH OH HO OH PGM FAST - O CH OH OH HO 2 H C 2 O O O - O P PGM SLOW
- 14. Enzymatic Reactions of Low Structural Specificity (CH ) -CH 3 2 O (CH ) -CH 3 2 OH ADH + + H + NADH NAD ADH CH -CH O CH -CH -OH 3 + + H + NADH NAD 3 2 Oxidation-Reducton
- 15. Enzymatic Reactions with Stereochemical CO H C 2 CO H C + H N 2 + 3 CH 3 H NH H C 3 H D-ALANINE 3 L-ALANINE CO H C 2 CH 3 O + NH + 4 Specificity D-AMINO ACID OXIDASE
- 16. + + CH -CH -OH + NAD CH -CH=O + NADH + H 3 2 3 ALCOHOL DEHYDROGENASE
- 18. Catalytic vs Binding Specificity As opposed to lock and key model, enzyme recognizes and binds transition state, better than substrate For enzymes recognizing a variety of structurally similar substrates, the tighter binding substrates often are catalyzed to product slower than weaker binding substrates
- 19. Enzyme regulation by metabolic end products