Chapter 2: Enzymes

Question 1

cofactor that acts as a electron carrier

Answer 1

NAD+ or NADP+

Question 2

enzyme features

Answer 2

1) do not interfere with the delta G of the reaction
2) lower the activation energy
3)increase rate of the reaction
4) are pH and temp sensitive

Question 3

6 types of enzyme based on mechanism:

Answer 3

oxidoreductases

Question 4

oxidoreductases

Answer 4

catalyse oxidation-reduction reactions. The electron donor is known as the reductant and the electron aceeptor as the oxidant.

enzymes with dehydrogenase or reducase in their names

Question 5

kinase

Answer 5

catalyse the transfer of a phosphate group, generally from ATP, to another molecule. It is a type of transferase enzyme.

Question 5

Oxidoreductases.

Answer 5

Catalyze oxidation reduction reactions, that is the transfer of electrons between biological molecules. The electron donor is known as the reductant and the electron acceptor is known as oxidant. Enzymes with dehydrogenase or reductase in the name.

Question 5

Transferases.

Answer 5

Catalyze movement of a functional group from 1 molecule to the other. I mean the transfer uses an example.

Question 6

Hydrolases

Answer 6

Catalyze the breaking of a compound into two molecules using the addition of water. The most common hydrolases it will be phosphatase which cleaves the phosphate group from another molecule. Other hydrolases are peptidases, nucleases and lipases, which break down proteins, nucleic acids and lipids.

Question 6

Lyases

Answer 6

Catalyze the cleavage of a single molecule into two products.

Question 6

Isomerases

Answer 6

Catalyze the rearrangement of bonds within a molecule. Keep in mind that I summarize this catalyzed reactions between stereoisomers as well as constitutional isomers.

Question 7

Ligases

Answer 7

Catalyze addition or synthesis reactions generally between large similar molecules and often require ATP.

Question 8

Impact on activation energy.

Answer 8

Catalysis exerts their effect by lowering the activation energy of a reaction. Most reactions catalyzed by enzymes are technically reversible, although the reversal may be extremely energetically unfavorable.

Question 8

Lock and key theory.

Answer 8

He suggested enzymes active site is already in the appropriate confirmation for the substrate to bind. The substrate can then easily fit into the active site like a key into a lock.

Question 8

Induced fit model.

Answer 8

This interaction requires energy and therefore this part of the reaction is endergonic. He starts with the substrate and enzyme active site that don’t seem to fit together. However, once the substrate is present and ready to interact with the active site. The molecule find that the induced form or transition state is more comfortable for both of them. The shape of the active site becomes truly complementary only after the substrate begins binding to the enzyme.

Question 9

Cofactors

Answer 9

Generally, inorganic molecules are metal ions and are often ingested as minerals.

Question 10

Coenzymes.

Answer 10

Small organic groups, the vast majority of which are vitamins, are derivatives of vitamins such as NAD+, FAD and coenzyme A. The water soluble vitamins include the B complex vitamins and the C vitamin. The fat soluble vitamins are ADE&K.

Question 10

Apoenzymes.

Answer 10

Enzymes without their cofactors.

Question 11

Holoenzymes

Answer 11

Enzymes with their cofactors.

Question 12

Prosthetic groups.

Answer 12

Tightly bound cofactors or consumes that are necessary for enzyme function.

Question 12

Kinetics in monomeric enzymes.

Answer 12

The concentration of the substrate and enzyme greatly affect how quickly a reaction will occur. As we slowly add more substrate, the rate of the reaction will increase. However, as we add more and more, we begin to level off and reach a maximum rate of reaction. Therefore, you cannot go any faster once it has reached saturation. At this rate, the enzyme is working on maximum velocity, denoted by Vmax. The only way to increase Vmax is by increasing the enzyme concentration.

Question 13

Michaelis-Menten equation.

Answer 13

V = Vmax [S] / Km + [S]

Km is understood to be the substrate concentration at which half of the enzyme active sites are full. Km Is the Michaelis constant and is often used to compare enzymes. The one with the higher Km, has the lower affinity for its substrate because it requires a higher substrate concentration to be half saturated. Low Km Reflects a high affinity for the substrate.

Question 14

Turnover number (kcat)

Answer 14

Vmax = [E] kcat

The ratio of kcat/km Please refer to as the catalytic efficiency of an enzyme. A large kcat or small Km Will result in a higher catalytic efficiency.

Question 14

Cooperativity

Answer 14

Cooperativity enzymes have multiple subunits in multiple active sites. Some units and enzymes may exist in one of two states: A low finity tense state (T) Or higher finity, relaxed state (R). Binding of the substrate encourages the transition of other subunits from the T state to the R state, which increases the likelihood of substrate binding by other subunits. Loss of substrate can encourage the transition from the R state to the T state and promote dissociation of substrate from the remaining subunits.

Question 15

Hill’s coefficient.

Answer 15

If Hill’s coefficient > 1 positively cooperative binding is occurring.

If Hill’s coefficient < 1 negatively cooperative binding is occurring.

If hill’s coefficient = 1 The enzyme does not exhibit cooperative binding.

Question 16

Temperature.

Answer 16

Enzyme catalyzed reactions tend to doubling velocity forever. 10°C increase in temperature until the optimum temperature is reached. For the human body this is 37°C. After this activity falls off sharply at the enzyme would the nature higher temperatures.

Question 17

PH.

Answer 17

The optimal pH is 7.4. Changes in pH can lead to denaturation of the enzyme.

Question 18

Salinity.

Answer 18

Increasing levels of salt can disrupt hydrogen and ionic bonds, causing a partial change in the confirmation of the enzyme and in some cases causing denaturation.

Question 19

Negative feedback.

Answer 19

It helps maintain homeostasis common. Once we have enough of a given product, we want to turn off the pathway that creates the product rather than creating more. Feedback inhibition The product made by into the active site of the enzyme or multiple enzymes that acted earlier as its biosynthetic pathway, thereby competitive inhibiting these enzymes and making them unavailable for use.

Question 19

Competitive inhibition.

Answer 19

Simply involves occupancy of the active site. Some shrink cannot access enzymatic binding sites if there is an inhibitor in the way. Competitively, vision can be overcome by adding more substrate to that substrate-to-inhibitor ratio. That way the enzyme will be more likely to bind substrate than inhibitor. It does not alter the value of Vmax because if enough substrate is added, it will outcompete the inhibitor and be able to run the reaction and maximum velocity. It does increase Km. This is because the substrate concentration has to be higher to reach half the maximizing mostly in the presence of the inhibitor.

Question 20

Non competitive inhibitors.

Answer 20

Bind to an alosthetic site instead of the active site, which induces a changing the enzyme confirmation. They cannot be overcome by adding more substrate. They bind equally well to the enzyme and the enzyme substrate complex. Adding and noncompetitive indicator decreases the measure of Vmax because there’s less enzyme available to react. It does not, however, alter the value of Km because any copies of things on there still active maintain the same affinity for their substrate.

Question 21

Mixed inhibition

Answer 21

Results when Inhibitor can bind to either the enzyme or the enzyme substrate complex but has different affinity for each. Mixed inhibitors do not bind to the active site, but at the allosteric site. He think he better preferentially binds the enzyme, it increases the Km. If the inhibitor binds to the enzyme-substrate complex, it lowers the Km.

Question 22

Uncompetitive inhibition

Answer 22

Binds to the enzyme-substrate complex and essentially locked the substrate in the enzyme, preventing its release. It must buy it the allosteric site. It lowers the Km and the vmax.

Question 23

Irreversible inhibition.

Answer 23

The active site is made unavailable for a prolonged period of time or the enzyme is permanently altered.

Question 24

Covalently modified enzymes.

Answer 24

Enzymes can be activated or deactivated by phosphorylation or dephosphorylation. Glycosylation, the covalent attachment of sugar moieties, is another covalent enzyme modification.

Question 24

Allosteric enzyme.

Answer 24

Enzymes that are allosteric have multiple binding sites. These are known as allostatic sites. Allosteric enzyme alternate between an active and inactive form. Molecules that bind to the allosteric site may be either allosteric activators or allosteric inhibitors. An activator will result in the shift that makes the active site more available for binding to the substrate, whereas inhibitor will make it less available.

Question 25

Zymogens.

Answer 25

They contain a catalytic (active) domain, and regulatory domain. The regulatory domain must be either removed or altered to expose the active site.