Ch. 6 Enzymes Part 1 (Exam 2) Flashcards
Kinetics, Catalysis, Enzymes, Rate of Reaction, Mechanism of Enzyme Catalysis
What is the relationship between high activation energy, reaction rate, and the number of collisions in a reaction?
High activation energy = lower reaction rate = lower # of collisions
In an uncatalyzed Boltzmann distribution vs. time, how does temp affect the number of particles/molecules at any given activation energy?
Lower temp = fewer reacting particles/molecules
Higher temp = more reacting particles/molecules
Under what condition can the particles/molecules in a Boltzmann distribution react?
The particles/molecules must have energy that surpasses the activation energy
How do catalysts affect reaction rate?
They increase reaction rate by lowering activation energy
What 2 things do catalysts not change?
1) Equilibrium position
2) Change in Gibbs energy
Define activation energy.
Energy needed for reactants to reach the transition state
Define transition state.
Midpoint between reactants and products
What happens to chemical bonds during the transition state?
Old bonds are breaking and new bonds are forming
What is another name for transition state?
Intermediate state
Why is the transition state the least stable phase on a reaction curve?
It is high energy
How does a catalyst affect the Boltzmann distribution of activation energy in terms of the amount of freely reacting particles?
Catalyzed activation energy has more reacting particles than uncatalyzed activation energy
What are enzymes?
Biological catalysts
In what form/shape will you mostly find enzymes?
Globular proteins
How do amino acids help active sites?
They lower the transition state energy
Give an example of how product-specific enzymes are.
They typically produce only one stereoisomer
What does a chemical reaction not change?
The enzyme
What are two important things about active sites?
1) Enzyme surface is binding location for substrate
2) Substrates are placed in precise orientation
What is another term for reactant?
Substrate
In what 2 ways do substrates bind to active sites?
Non-covalently and reversibly
What changes when a substrate binds to an enzyme,, and what is this called?
The 3D shape known as the enzyme-substrate complex (ES)
What is the induced fit model?
The complimentary fit of the transition state
How does the induced fit model aid in transition state formation?
The substrate fits into the enzyme forming the ES, which aids in transition state formation
What are 2 important factors in a substrate binding to an enzyme?
1) Proximity
2) Orientation
What is the proximity effect?
It places substrates closer together so that the # of collisions increases to, in sum, increase the reaction rate
What is the orientation effect?
It places substrate into the maximally reactive conformation/shape
