Sections
Enzymes
Enzyme-Substrate Complex
Lock and Key Vs. Induced Fit Models
Optimal Enzyme Conditions
Activation Energy
Types of Enzymes
Cofactor
Catalysis
Electrostatic and Metal Ion Catalysis
Covalent Catalysis
Reaction Rate
Enzyme Kinetics
Rate Constants and Rate Law
Reaction Orders
Rate Constant Units
Initial Velocity
Vmax Enzyme
Km Enzyme
Steady-State Conditions
Michaelis-Menten Assumptions
Michaelis-Menten Equation
Lineweaver-Burk Plot
Michaelis-Menten vs. Lineweaver-Burk Plots
Shifting Lineweaver-Burk Plots
Calculating Vmax
Calculating Km
Kcat
Specificity Constant

Concept #1: Introduction to Covalent Catalysis 

Practice: An enzyme has two key catalytic residues, Glu 35 (pKa= 5.9) and Asp 52 (pKa= 4.5). Which of the following is likely true about the mechanism for this enzyme if the optimum pH = 5.2?

Practice: Which of the following mechanisms is not used by enzymes for catalysis?

a) General Acid-base catalysis. 

b) Induced fit of enzyme to transition state. 

c) Destabilizing the transition state. 

d) Providing complementary electrostatics.

e) Binding of metal ions.

f) Specific Acid-Base Catalysis

g) a & c.

h) c & f

i) b, c & f

Practice: Which catalytic mechanism uses an electrophilic cofactor to stabilize a negative charge on an intermediate?

Practice: Which of the following catalytic mechanisms proceeds via noncovalent interactions?

Practice: Suppose that the covalent catalytic mechanism of an enzyme depends on a single active site amino acid (Cys), whose pKa = 8.3. A mutation in a nearby amino acid residue of the enzyme only slightly alters the microenvironment so that the pKa of the Cys residue increases to 10.3. Would this mutation cause the enzyme-catalyzed reaction rate to increase or decrease? Explain.