Enzymes as catalysts

Question 1

Enzymes do what

Answer 1

Speed up reaction without being change during the reaction or affecting the equilibirum

Question 2

Chemical catalysts vs enzyme catalysts

Answer 2

enzyme don’t usually produce side reactions whereas chemical ones do

Question 3

Describe how the enzyme binds the substrate and the energy involved

Answer 3

The substrate binds the enzyme at the active site. The enzyme will then conform more closely to the shape of the substrate. Then the enzyme will match the transition state of the substrate pushing it towards that and then it will will push the substrate to its product form and this whole process is energetically favorable so it will push it forward to completion.

Question 4

Factors that affect enzyme activity

Answer 4

1. substrate concentration
2. Temperature
3. pH

Question 5

how does substrate concentration affect enzyme activity

Answer 5

rate of enzyme-catalyzed reaction will increase the more that substrate is added until a certain point when Vmax is reached. All available active sites are saturated.

Question 6

temperature

Answer 6

reaction rate will increase as temperature increases until a certain temp is reached than anything over than maximum temp will denature the enzyme.

Question 7

pH

Answer 7

each enzyme works best at a specific pH, and anything over or under this ideal pH can denature the enzyme

Question 8

oxidoreductases

Answer 8

add or remove one or more electron from or to substrates (often called dehydrogenases)

Question 9

transferases

Answer 9

transfer a group from one substrate to another (ex. kinases)

Question 10

hydrolases

Answer 10

carry out the hydrolysis of substrates (ex. phosphtases)

Question 11

lyases

Answer 11

carry out the cleavage of a molecule into parts

Question 12

isomerases

Answer 12

rearrange a substrate into an isomeric form

Question 13

ligases

Answer 13

join molecules together by condensation, usually eliminating water

Question 14

gibbs free energy

Answer 14

it is the difference between energy of the products and the substrates

if it is negative is is favorable and occurs spontaneously

enzymes change the rate at which equilibirum is achieved but they do not change equilibirum

Question 15

energy coordinate diagram

Answer 15

the bigger the activation energy the slower the conversion from substrate to product.

enzymes can lower this activation energy

enzymes do not change delta G

Question 16

four ways enzymes increase rate of reaction

Answer 16

1. binding energy: the binding of the substrate with the active site liberates energy, which brings the substrate closer to its transition state quicker
2. proximity: the binding of the enzyme and substrate increases concentration within active sites. If they are already in contact the reaction will occur quicker. They don’t have to randomly collide with each other if they are already in contact with each other.
3. Induced Fit: Substrate binds to enzyme, which conforms tertiary structure of enzyme, which in turn further increases the affinity of the enzyme for the substrate and pushes the substrate towards the transition state
   4: The geometry of the substrate will allow it to slide right into the active site easier and increase the reaction rate.

Question 17

serine proteases

Answer 17

• enzymes that hydrolyze specific peptide bonds in proteins (splits the protein into small polypeptides)
• hydrolyze amide bonds adjacent to specific amino acid residues
• digestion
• synthesized in the pancreas as pro-enzymes or zymogens that are initially inactive. Activated after released from the pancreas

Question 18

chymotrypsin

Answer 18

favors aromatic residues and large non polar residues

Question 19

trypsin

Answer 19

negatively charged residue in its binding pocket that favors lysine and arginine

Question 20

elastase

Answer 20

favors binding of alanine or glycine