Enzymes and Enzyme Kinetics

Question 1

Enzymes are usually (but not always) ____

what else can they be

Answer 1

Proteins

some are RNA

Question 2

Most intracellular reactions will not proceed in appreciable rates in the absence of ____

Answer 2

Enzymes

Question 3

General Behavior of Catalysts

regarding reaction coordinate

Answer 3

Increase rate of readction withouth affecting equilibrium

Catalyst behavior

Question 4

Syntethic Catalyst and Enzymes why use enzymes

Answer 4

1. Enzymes are more specific
2. Enzymes are active under mild conditions
3. Enzymes can be used to synthesize optically active substances

Question 5

6 Classes of Enzymes

and respective reactions

Answer 5

1. Oxidoreductases - redox rxns
2. Transferases - group transfer
3. Hydrolases - break bonds with H2O addition
4. Lyases - Addition to double bonds
5. Isomerases - Isomerization rxns
6. Ligases - Formation of bots with ATP cleavae

Question 6

Active sites involve a ___ portion of the enzyme surface

Answer 6

small

Question 7

Basic Type of Inhibitions

Principle and Graphs

Answer 7

Competitive: Inhibitor molecuel competes with the subtrate for the active site of the enxyme
Uncompetitive: The inhibitor molecule binds to the ES complex and stops the reaction
Noncompetitive: The inhibitor binds to a site on the enzyme that is not the active site whcih prevents it from binding to substrate

Question 8

Substrate Inhibition

Answer 8

Occurs when enzyme activity decreases as the concentration of substrate increase beyond a certain point

Question 9

Substrate Activation

Answer 9

Occurs when activity of enzyme ncreases as the concentration of susbstrate increases

Question 10

End-product inhibition

Answer 10

Occurs when the final product of a metabolic pathway acts as an inhibitor of one of the enzymes earlier in the pathway

Question 11

Irreversible Inhibition

Answer 11

Occurs when an ihbitior permanetly binds to an enzume by forming a covalent bond or an irreversible change.

Question 12

pH effects on Enzyme Activity

2 Main effects

Answer 12

1. Alters proteint structure conformation
2. Ionizes the active site or substrate
   pH must be controlled by buffering as most enymatic reactions result in pH change

Question 13

Temperature effects on Enzyme Activity

2 Main effects and Thermophilic microorganisms

Answer 13

1. Increased reaction rate
2. Increased denaturation rate
   Themophilic microorganisms possess enzymes with high optimum reaction temperatures

follows arrhenius-type law

Question 14

Enzymes vs Industrial Catalysts

4 Cases where enzymes are better

Answer 14

Enzymes only when few steps are involved (1~3)
If reaction must be run under mild conditions
Processing sensitive substrates
High Specificity
Production of optically active molecule needed

Question 15

Enzymes vs Industrial Catalysts

3 Advantages of Industrial Catalysts

Answer 15

Cost
Stability
Less likely to be inhibited

Question 16

Industrial Enzyme use

3 products

Answer 16

High Fructose Corn Syrup Production starch → glucose enzymes.
Cheese Making:: Rennin is an acid protease that induces clotting
Detergents:: Largest single use of industrial enzymes

85% are hydrolytic enzymes

Question 17

Advantages and Disadvantages of using immobilized enzymes

Answer 17

Advantages: More resisteant to denaturation and proteolysis. Easier to recover (use again).
Disadvantage: Immobilization cost must be less than savings from advantages

Question 18

4 Methods of Immobilization

Answer 18

Covalent Attachement
Adsorption
Covalent crosslinking
Entrapment/Encapsulation

Question 19

Immobilization can lead to ____ limitations which means that observed kinetics are not “_”

Answer 19

diffusion
true kinetics

Question 20

Linewaver Burk Plot

Answer 20

Good for finding Vmax

Question 21

Eadie Hofstee Plot

Answer 21

Better at determing K because intercept and slope vary less

Question 22

Michaelis Menten Plot

Answer 22