enzymes

Question 1

what is required for enzymes to recognize and bind substrates

Answer 1

• same polarity between enzyme and substrate
• matches shape to maximize contact
• match of charged groups
• match of H-bond donor and acceptor

Question 2

what do enzymes do

Answer 2

recognize and bind proteins and catalyze reactions on them

Question 3

target of an enzyme

Answer 3

substrate

Question 4

without catalysts what random events do reactions depend on?

Answer 4

• molecules must collide
• must be in the right orientation
• reacting molecules require threshold energy
  if these conditions are met reaction MAY occur but depends on chance

Question 5

Arrhenius equation

Answer 5

states that rate is dependent on collision frequency, probability, activation energy and temperature

Question 6

activation energy

Answer 6

Ea is the energy that must be put into a reaction at initial steps to break distort bonds

Question 7

what makes rate of reaction increase?

Answer 7

• increasing Z (collision frequency)
• increasing p (probability factor)
• decreasing Ea (activation energy)
• increasing temperature (T)

Question 8

true or false - enzymes eliminate randomness of collision

Answer 8

True

Question 9

proximity effect

Answer 9

enzyme binds substrate in active site which holds them in the close together long enough for the reaction to proceed
- increases Z
-physical effect

Question 10

orientation effect

Answer 10

enzyme holds substrates in the correct orientation so reactive groups are ideally aligned
- increases p
- physical effect

Question 11

entropy

Answer 11

randomness of reactions relates to entropy
- enzymes decrease activation entropy of reaction

Question 12

Enzymes and activation energy

Answer 12

• enzymes use chemical catalysts to speed up rxn by lowering Ea
• Ea can be lowered by finding a better chemical pathway for rxn

Question 13

nucleophilic catalyst

Answer 13

enzyme that speeds up reaction by providing a better nucleophile

Question 14

electrophilic catalyst

Answer 14

provides a better electrophile or prosthetic group
- initiates reaction by withdrawing electrons from substrate

Question 15

general acid catalysis

Answer 15

amino acid side chain donates H+ to the reaction

Question 16

general base catalysis

Answer 16

amino acid that removes H+ from the reaction

Question 17

transition state

Answer 17

an intermediate configuration at which the potential energy has a maximum value
- key atoms may change shape

Question 18

how can an enzyme help the transition state

Answer 18

by binding the substrate in the ideal shape for the transition state

Question 19

how are activation energy and transition state related

Answer 19

less activation energy is needed the enzyme active site is complementary to the transition state