Enzymes

Question 1

What are enzymes?

Answer 1

Catalysts

Question 2

What do catalysts do?

Answer 2

Increase the rate of a reaction repeatedly and decrease activation energy of a reaction, and are not consumed by the reaction

Question 3

What do enzymes not do?

Answer 3

Change the ratio of the concentrations of products to reactants at equilibrium and alter the amount of energy consumed or liberated in the reaction

Question 4

What special environment is provided by an enzyme’s active site?

Answer 4

catalysis occurs when substrate is held at the active site

Question 5

What functional groups can be involved in catalysis?

Answer 5

almost all alpha amino and carboxyl groups are tied up in peptide bonds R groups

Question 6

Some enzymes employ _________ or _________ groups at their active sites

Answer 6

coenzymes; prrosthetic

Question 7

Coenzymes

Answer 7

metals or small organic molecules not covalently bound to protein

Question 8

prosthetic groups

Answer 8

small organic molecules typically covalently linked to protein

Question 9

How do enzymes catalyze biochemical reactions?

Answer 9

involves basic principles of organic chemistry

Question 10

Do enzymes physically interact with their substrates to affect catalysis?

Answer 10

Yes

Question 11

E

Answer 11

Enzyme

Question 12

S

Answer 12

Substrate

Question 13

ES

Answer 13

Enzym/substrate complex

Question 14

ES*

Answer 14

Enzyme/transition state complex

Question 15

P

Answer 15

Product

Question 16

EP

Answer 16

Enzyme/Product complex

Question 17

What do substrates bind to?

Answer 17

Enzyme’s active site

Question 18

How do substrates bind?

Answer 18

by Hydrogen bonding, hydrophobic interactions and ionic interactions

Question 19

Lock and key model

Answer 19

substrate (key) fits into a perfectly shaped space in the enzyme (lock)

Question 20

Induced fit model

Answer 20

substrate fits into a space in the enzyme, causing the enzyme to change conformation

Question 21

Following catalysis, what happens to the products?

Answer 21

binds less tightly or no longer fits in the active site and is released

Question 22

To assay an enzyme, you could measure what?

Answer 22

the 1. appearance of colored product made from an uncolored substrate
the 2. disappearance of a UV-absorbent substrate that is converted into a non-UV-absorbent substrate
3. the appearance of radioactive product made from a radioactive substrate

Question 23

Continuous assays units

Answer 23

[P] vs time

Question 24

End Point Assay units

Answer 24

[P] vs time

Question 25

________ concentration of substrate = higher concentration of product

Answer 25

lower

Question 26

Constant [E] units

Answer 26

[P] vs time

Question 27

Velocity is dependent on what?

Answer 27

Concentration of substrate

Question 28

Converting _____ into product slows down velocity

Answer 28

substrate

Question 29

Hyperbolic (Michaelis-Menten plot)

Answer 29

V vs [S]

Question 30

Michaeles-Menten equation

Answer 30

V = Vmax [S] / KM + [S]

Question 31

Vmax

Answer 31

the maximum rate that can be observed in the reaction

Question 32

KM

Answer 32

Michaelis constan that is related to the affinity of the enzyme for the substrate