Lecture 9. Enzymology 1

Question 1

What are the 9 characteristics of an enzyme ?

Answer 1

1. Preferred substrate
2. pH
3. Temperature
4. Localisation
5. Reaction catalysed
6. Mechanism of the reaction
7. Physiological role and control or regulation of activity
8. Impact of upregulation
9. Inhibition or absence

Question 2

What is enzyme kinetics ?

Answer 2

The study of the rate of enzyme catalysed reactions

Question 3

What are catalysts ?

Answer 3

Substance that speeds up a reaction but that in itself is not consumed during the reaction (may be changed transiantly)

Question 4

Are all biological catalysts proteins ?

Answer 4

Most are, some may be RNA

Question 5

What causes enzyme specificity ?

Answer 5

The precise interaction of the enzyme and substrate

Question 6

What reaction is catalysed by hydrolase and give an example ?

Answer 6

1. Hydrolysis

2. Lipase

Question 7

What reaction is catalysed by isomerase and give an example ?

Answer 7

1. Rearrangement of atoms

2. Phosphoglucoisomerase

Question 8

What reaction is catalysed by ligase/polymerase and give an example ?

Answer 8

1. Join two or more chemicals together

2. Acetyl-CoA synthetase

Question 9

What reaction is catalysed by lyase and give an example ?

Answer 9

1. Split compounds without water

2. Fructose 1, 6 - biphosphate aldose

Question 10

What reaction is catalysed by oxidoreductase and give an example ?

Answer 10

1. Transfer electrons and H+ from one molecule to another

2. Lactic acid dehydrogenase

Question 11

What reaction is catalysed by transferase and give an example ?

Answer 11

1. Move functional groups between molecules

2. Hexokinase

Question 12

What does trypsin cleave ?

Answer 12

The carboxyl side of lysine or argine

Question 13

What does thrombin cleave ?

Answer 13

The arginine glycine bonds in particular sequences only

Question 14

What are cofactors ?

Answer 14

Small molecules that some enzymes require for activity

Question 15

What are the two types of cofactors ?

Answer 15

1. coenzymes

2. metals

Question 16

What are prosthetic groups ?

Answer 16

Tightly bound coenzymes

Question 17

What is a holoenzyme ?

Answer 17

An enzyme with its cofactor

Question 18

What is an apoenzyme ?

Answer 18

An enzyme without a cofactor

Question 19

What is gibbs free energy ?

Answer 19

A thermodynamic function that describes the potential energy available for work

Question 20

What does the free energy change tell us ?

Answer 20

The spontaneity but not the rate of the reaction

Question 21

What is an exergonic reaction ?

Answer 21

A reaction which occurs without the input of energy, or spontaneously only if the change in gibbs energy is negative

Question 22

What is an endergonic reaction ?

Answer 22

A reaction will not occur spontaneously only if the change in gibbs energy is positive

Question 23

What is delta G independent of ?

Answer 23

How the reaction occurs

Question 24

What do highly exergonic reactions have ?

Answer 24

Large K’eq values

Question 25

What do highly endergonic reactions have ?

Answer 25

Small K’eq values

Question 26

What is a transition state ?

Answer 26

A molecular form that is no longer substrate but not yet product

Question 27

What is the activation state ?

Answer 27

The energy required to form the transition state from the substrate

Question 28

Where do enzymatic reactions take place ?

Answer 28

The active site

Question 29

What is the active site made from ?

Answer 29

Amino acids from the primary structure

Question 30

What does the interaction of the enzyme and substrate at the active site involve ?

Answer 30

Multiple weak interactions

Question 31

What does enzyme specificity depend on ?

Answer 31

The molecular architecture at the active site

Question 32

What are sequential reactions ?