BCH Kaplan Book

Question 1

Michaelis-Menten Equation

Answer 1

relates velocity of enzyme to substrate concentration

v = (Vmax[S]) / Km+[S]

Question 2

What can be concluded when the reaction rate is equal to half of Vmax?

Answer 2

Km = [S]

Question 3

higher Km means

Answer 3

enzyme has lower affinity for substrate
- requires higher substrate concentration to negate

THINK: competitive inhibitor

Question 4

lower Km means

Answer 4

enzyme has HIGHER affinity for substrate

- requires less substrate concentration to negate

Question 5

cooperativity (enzyme binding)

Answer 5

shows a sigmoidal shaped kinetics among substrate binding sites

Think of cooperative enzyme kinetics like a party:

• more people arrive: atm = more relaxed
• as more people start going home, party dies down and more people are encouraged to go home so the tense hosts can clean up

enzymes that show cooperativity are often regulatory enzymes like pfk-1 (phosphofructokinase-1)