Catalytic Mechanisms Flashcards
5 Mechanisms of Enzyme Catalysis
Proximity & Orientation, General Acid/Base, Transition State Stabilization, Covalent, Prosthetic Group
Describe Proximity & Orientation Catalysis
Increases local concentration of substrate at active site
Intramolecular is faster than intermolecular
Conformational preorganization increases rate
Describe Transition State Stabilization
Enzyme bound to transition state and decreases activation energy required to reach the transition state
Describe Acid Base Catalysis
+/- Hydrogen ions to aid bond formation/breaking
Amino Acids: Glu, Asp, Arg, Lys, Cys, Ser, Thr, Tyr, His
Describe Covalent Catalysis
Enzyme covalently binds to substrate to make the intermediate more reactive towards the final acceptor
Decreases energy of activation of later transition state
Describe Prosthetic Group Catalysis
Activate substrates by increasing local electronegativity
Ionic bonds stabilize charged transition state
Name the 6 Major Enzyme Classes
Oxidoreductase, Hydrolase, Ligase, Lyase, Isomerase, Transferase
Describe Oxidoreductases
Enzymes that transfer electrons and usually have common cofactors (NAD, FAD, etc)
Describe Transferases
Enzymes that transfer a group from one molecule to another
ALL KINASES ARE TRANSFERASES
Describe Hydrolases
Enzymes that transfer functional groups to water molecules
Describe Lyases
Enzymes that break C-C, C-O, C-N, etc by elimination to give double bonds, rings, or add groups to double bonds`
Joining 2 groups usually by breaking bonds and forming new double bonds
Describe Isomerases
Enzymes that transfer groups to their isomeric form
Describe Ligases
Enzymes that create C-C, C-O, C-N, etc by condensation reactions coupled to ATP or similar
Joining 2 molecules by creating a bond
