Enzymes

Question 1

Biological catalyst unchanged by the reactions they catalyze and are reusable.

Answer 1

Enzymes

Question 2

Catalyzes oxidation reduction reactions and involved in transfer of electrons.

Answer 2

Oxioreductase

Question 3

Catalyzes the transfer of functional groups from molecule to molecule.

Answer 3

Transferase

Question 4

Catalyzes hydrolysis reactions.

Answer 4

Hydrolase

Question 5

Catalzyes cleavage without the addition of H2O.

Answer 5

Lyases

Question 6

Enzyme that rearranges bonds within a molecule. (causing the interconversion of isomers)

Answer 6

Isomerase

Question 7

Responsible for joining two large biomolecules together (often of the same type).

Answer 7

Ligase

Question 8

What is the reason an enzyme would be necassary for a biological reaction?

Answer 8

Increases the rate of reaction (thereby lower the activation and energy). Enzymes only change the kinetics of a reaction.

Question 9

What does an enzyme not change?

Answer 9

1. Delta G (Gibbs Free energy)
2. Enthalpy
3. Equilibrium constant (however, they do change rate at which equilibrium is reached )

Question 10

Molecule upn which an enzyme acts

Answer 10

Substrate

Question 11

How do enzymes increase the rate of reaction?

Answer 11

By stabilization transition state via enzyme substrate complex

Question 12

Site of catalysis on an enzyme

Answer 12

active site

Question 13

What are the two competing theories that explain how enzymes and substrates interact.

Answer 13

1. Lock and key theory
   
   1. Hypothesizes that enzyme and substrate are exactly complimentary
2. Induced-Fit Model
   
   1. Hypothesizes that enzymes and substrate undergo conformational changes to fully interact (once they come together)

Question 14

Non-protein molecules that bind to the active site of enzymes and participate in the catalysis of the reaction. Are sometimes required for enzyme function. Also, these molecules often carry a charge.

Answer 14

Coenzyme/Cofactors

Question 15

Generally inorganic molecules or metal ions (think minerals) that may be necessary for enzyme function.

Answer 15

Cofactor

Question 16

Organic molecules that may be necessary for enzyme function. Are often vitamins or derivatives of vitamins

Answer 16

Coenzymes

Question 17

What are two types of water soluble vitamins?

Answer 17

1. B Vitamin Complex
2. Ascorbic Acid

(must be ingested regularly because they are easily excreted)

Question 18

What are examples of fat soluble vitamins

Answer 18

A, D, E, K

(better regulated within the body by partition coefficients (quantify its abiity to dissolve in polar vs. non-polar environment))

Question 19

Explain Saturation Kinetics for Enzymes

Answer 19

For a given enzyme concentration, as substrate concentration increases, so does the rate of reaction until V_max is reached. Once Vmax is reached, the only way to further increase the rate is by increasing th enzyme concentration

Question 20

What is the michaelis mentetn equation?

Answer 20

Question 21

What does the Michaelis Menten (K_m) constant represent?

Answer 21

Substrate concentration at half V_max

Question 22

A _____ K_m represents a high affinity for an enzymes substrate. A _____ K_m represents a low affinity for its substrate.

Answer 22

1. Low
2. High

Question 23

What is the equation for the lineweaver burk plot?

Answer 23

This equation is equal to y = mx + bf

where m = slope

x = x-intercept

b = y-intercept

Question 24

In the lineweaver burk-plot, and increase in substrate concentration equals a decrease in the ___________. Similiarly, an increase in rate of reaction (v) will equal a decrease in the _________.

Answer 24

1. Inverse of the substrate concentration
2. Inverse of the rate of reaction

Question 25

This type of substrate interaction displays a sigmoidal curve because of the change in activity with substrate binding.

Answer 25

Cooperativity (when one substrate binds, this increases the enzymes affinity for more substrates to bind)

Question 26

List three things that can affect enzyme activity.

Answer 26

1. Temperature
2. pH
3. Salinity (osmolarity)

An increase in these can denature the protein structure of an enzyme, ultimately rendering it inactive.

Question 27

List the 4 types of inhibition.

Answer 27

1. Competive
2. Un-Competitive
3. Non-Competitive
4. Mixed

Question 28

What is competibe inhibition? How does it affect Vmax and K_m?

Answer 28

1. Inhibition where inhibitor is so similiar to the substrate that it can bind to the active site of the enzyme, ultimately preventing the substrate from binding
2. K_m Increases because affinity decrease
   
   1. B/c more substrate must be added to reach V_max
3. No change in V_max
   
   1. _​B/c if enough substrate is added, it will be able to outcompete inhibitor and reach V_max

Question 29

What is uncompetitive inhibition? How does it affect K_m and V_max?

Answer 29

1. When an inhibitor binds to to an allosteric site of the ES-Complex, locking the substrate in the enzyme and preventing its release.
2. Decrease K_m
3. Decreases V_max

Question 30

What is noncompetitive inhibition? How does it affect Km and Vmax?

Answer 30

1. Binding of an inhibitor to allosteric site on enzyme or ES-complex
   
   1. Has equal affinity for ES-complex and enzyme
   2. Causes conformational changes to enzyme so that substrate cannot bind to the enzyme
2. K_m is unchanged
3. V_max is decreased

Question 31

What is mixed inhibition? How does it affect Km and Vmax?

Answer 31

1. Inhibitor binds to an allosteric site on the ES-Complex or Enzyme, but has varying affinities for both
   
   1. If it has a higher affinity for ES complex
      
      1. Decrease in K_M
      2. Decrease in Vmax
   2. If it has a higher affinity for Enzyme
      
      1. Increase in K_m
      2. Decrease in V_max

Question 32

Secreted in an inactive form and activated by cleavage

Answer 32

Zymogen

Question 33

Irreversible Inhibition

Answer 33

Altered enzyme where active site is unable for prolongued period of time or permanantly.