Chapter 8.3.1 (Exam 2) Enzymes Flashcards
Enzymes Speed Up Biochemical Transformations
Describe catalysts.
Catalysts increase rates of chemical reactions
The catalyst is not altered by the reactions
Most biological catalysts are enzymes (protein) that act as a framework in which reactions can take place
Why are some reactions slower than others?
Some reactions are slow because of an energy barrier
Describe activation energy (Ea).
The amount of energy required to start the reaction
Activation energy puts the reactants in a reactive mode called the transition state (like a ball at the top of a hill)
What are transition state intermediates created by?
Activation energy changes the reactants into unstable forms with higher free energy
Where does activation energy come from?
Activation energy can come from heating the system.
How do enzymes lower the energy barrier?
Enzymes lower the energy barrier by bringing the reactants together
Describe the structure of enzymes.
Enzymes are highly specific
Reactants are called substrates
Substrate molecules bind to the active site of the enzyme
The 3D shape of the enzyme determines the specificity
What is the specific 3D shape of enzymes determined by?
The functional groups of their amino acids
What is the enzyme-substrate (ES) complex held together by?
The enzyme-substrate complex (ES) is held together by hydrogen bonds, electrical attraction, or covalent bonds
How does binding to a substrate affect an enzyme?
The enzyme may change while bound to the substrate but returns to its original form
How do enzymes affect a reaction?
Enzymes lower the energy barrier for reactions
The final equilibrium does not change, and ∆G does not change
Enzymes can increase reaction rates by 1 million to 1017 times
What are the six categories of enzymes?
Crank up the AE, it’s a LIL HOT in here…
Ligases
Isomerases
Lyases
Hydrolases
Oxidoreductases
Transferases
