Enzymes

Question 1

enzymes convert what to products while remaining unchanged themselves?

Answer 1

substrates

Question 2

what are enzymes?

Answer 2

catalysts that convert substrates to product while remaining unchanged themselves

Question 3

what are reacts in enzymes called

Answer 3

substrates

Question 4

Name an enzyme that isnt a protein

Answer 4

RNA

Question 5

What are the 4 main advantages of biocatalysis over inorganic catalysts?

Answer 5

• Greater reaction specificity, so avoids side products
• milder reaction conditions
• higher reaction rates
• capacity for regulation

Question 6

how are enzymes classified?

Answer 6

on the types of reactions that they catalyse

Question 7

what does lyases do

Answer 7

group elimination to form double bonds

Question 8

what do ligases do

Answer 8

bond formation coupled with ATP hydrolysis

Question 9

what does bromelain do

Answer 9

an enzyme that facilitates hydrolysis of proteins

Question 10

Proteolytic enzymes do what

Answer 10

catalyse the hydrolysis of peptide bonds

Question 11

what type of enzymes illustrate the range of enzyme specificity

Answer 11

proteolytic enzymes

Question 12

enzymes do not alter what

Answer 12

The deltaG of a reaction

Question 13

Free energy is what

Answer 13

measure of energy capable of doing work

Question 14

Change in free energy when a reaction occurs is symbolised by what

Answer 14

DeltaG

Question 15

The more exergonic a reaction, the larger or smaller the equilibrium constant will be?

Answer 15

Larger

Question 16

The more endergonic a reaction, the larger or smaller the equilibrium constant will be?

Answer 16

Smaller

Question 17

the equilibrium constant is directly proportional to what?

Answer 17

To DeltaG

Question 18

Is deltaG positive or negative for an endergonic reaction?

Answer 18

Positive

Question 19

association rate is what?

Answer 19

association rate constant x concA x ConcB

Question 20

dissociation rate is what

Answer 20

dissociation rate constant x ConcAB

Question 21

At equilibrium, what is the relationship between association rate and dissociation rate?

Answer 21

Association rate = Dissociation rate

Question 22

enzymes increase reaction rates by decreasing what

Answer 22

Activation energy

Question 23

what is a transition state

Answer 23

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

Question 24

What is the activation energy

Answer 24

the energy required to form the transition state from the substrate

Question 25

Where does catalysis take place on the enzyme

Answer 25

Active site

Question 26

How do enzymes catalyse reactions in terms of transition states

Answer 26

They stabilise transition states

Question 27

Enzymes bring substrates together to form what at the active site?

Answer 27

form an enzyme-substrate complex at the active site

Question 28

What promotes the formation of the transition state?

Answer 28

Interaction of the enzyme and substrates at the active site

Question 29

What is the specificity of the an enzyme due to

Answer 29

To the precise interaction of the substrate with the enzyme

Question 30

The active site is what and formed by what

Answer 30

is 3D cleft formed by groups that come from different parts of the amino acid sequence

Question 31

how are substrates bound to enzymes (what bonds)

Answer 31

multiple weak noncovalent interactions

Question 32

specificity of binding is defined by what

Answer 32

3D structures of the active sites and substrates

Question 33

what is excluded from the active site unless it is a reactant?

Answer 33

water

Question 34

What character enhances the binding of the substrate as well as catalysis?

Answer 34

Non polar character

Question 35

what are the 2 models for the interaction of enzymes with their substrates

Answer 35

Lock and Key | Induced Fit Model

Question 36

Hexokinase undergoes what on substrate binding

Answer 36

Induced fit

Question 37

What is the energy released upon interaction of the enzyme and substrate?

Answer 37

Binding energy is the free energy released

Question 38

When is binding energy the greatest?

Answer 38

When the enzyme interacts with the transition state, facilitating the formation of the transition state

Question 39

Binding energy is a major source of free energy used by enzymes to do what

Answer 39

lower activation energies of reaction

Question 40

Enzymes being binded to transition states best was proposed by who

Answer 40

Linus Pauling 1946

Question 41

Enzyme active sites are what to the transition state of the reaction?

Answer 41

complementary

Question 42

Enzymes bind what better than substrates

Answer 42

Transition state

Question 43

Describe the binding energy in terms of the stickase exampel

Answer 43

Free energy required to draw the stack into the bent shape is offset or paid for by interactions between E and S in the transition state

Question 44

What are inhibitors of enzymes

Answer 44

transition state analogs

Question 45

Racemization of proline goes through a transition state in which the alpha carbon is what

Answer 45

trigonal

Question 46

Pyrrole 2 carboxylic acid had what geometry

Answer 46

Trigonal

Question 47

The similarity between pyrrole 2 carboxylic acid and racemization of proline means that pyrrole 2 carboxylic acid is what

Answer 47

Transition state analog and a potent inhibitor of proline racemase

Question 48

Summary of enzymes

Answer 48

- Reactions will proceed only if the free energy difference between reactant (substrate) and product is negative, however the rate may be very slow due to large activation energy required to reach the Transition state. - Enzymes lower the activation energy by providing an alternative pathway for the reaction to proceed. - Enzymes affect the rate of reaction but not the equilibrium position. They catalyse the forward as well as the reverse reaction - Enzymes are not altered in the reaction and can be re-used - Enzymes stabilise the transition state. Binding energy offsets the activation energy. - Enzymes differ from other catalysts in that they are specific for the substrate. They also work at much milder conditions (pH 7 and 370C)