1. Modes of Enzymatic Catalysis 1._________________ modes A.General _______________ Catalysis B.__________________ Catalysis 2.___________________ modes A.______________________ Effects B.__________________________________

2. 1. Chemical Modes of Catalysis Reaction acceleration is achieved by catalytic __________________ A general _______ (B:) can act as a __________________________ Can remove a proton from water and thereby generate the equivalent of OH- in neutral solution Can produce a stronger nucleophilic reactant (X: - ) A. General Acid-Base Catalysis

3. A general ________ (BH + ) can __________________ A covalent bond may break more easily if one of its atoms is protonated (below) B. ________________________ Catalysis All or part of a substrate is _________ covalently to the enzyme to form a reactive intermediate Can be used for ______________________________ A-X + EX-E + A X-E + BB-X + E

4. Example: Sucrose phosphorylase Step one: a glucosyl residue is transferred to enzyme Step two: Glucose is donated to phosphate *(Sucrose is composed of a glucose and a fructose) 2. _________________ of Enzymatic Catalysis Binding forces utilized for catalysis – _______________________ _______________________________________________________ 1. Charge-charge interactions 2. Hydrogen bonds 3. Hydrophobic interactions 4. Van der Waals forces

5. A. The Proximity Effect - __________________________ substrate molecules in the active site (1) Reduces their degrees of freedom (2) Results in a ___________________________________ (3) The relative _______________________ (“effective molarity”) predicts the rate acceleration expected due to this effect

6. B.Transition-State (TS) Stabilization transition states bind more tightly than substrates The enzyme ____________________, forcing it toward TS An enzyme must be complementary to the TS Enzymes may bind their transition states _____________ times more tightly than their substrates

7. Transition-state (TS) __________________ Stable compounds whose structures resemble _____________ _________________________ 2-Phosphoglycolate, a TS analog for the enzyme triose phosphate isomerase Can be used medically as _______________________________

8. ________________________ Reactions Enzyme rates can approach the _____________________ of the rate of diffusion of two molecules in solution Under physiological conditions the encounter frequency is about 10 8 to 10 9 M -1 s -1 A few enzymes have rate-determining steps that are roughly as fast as the binding of substrates to the enzymes Triose Phosphate Isomerase (TPI)

9. Properties of ________________________ Includes Trypsin, Chymotrypsin,Elastase Many digestive proteases similar in ________________ structure Chymotrypsin, trypsin and elastase - _______________ structure Active site substrate specificities differ due to relatively small differences in __________________________________

10. Serine Proteases Use Chemical and Binding Modes of Catalysis ______________ (__ amino acids) - ____ ____ ____