Enzymes

Question 1

Enzymes enhance reaction _______ but do not change the ________.

Answer 1

Rates; Equilibrium

Question 2

What is the name of the enzyme that is used as a monitor for liver and kidney disease? It is normally a cytoplasmic enzyme most abundant in liver and is released into the blood after liver damage.

Answer 2

Alanine amino transferase (ALT or ALAT)

Question 3

Enzymes lower free energy of activation by stabilizing ______?

Answer 3

The transition state

Question 4

What are transition state analogs?

Answer 4

Stable molecules that look similar to the transition state, often used to make drugs.
EX = allopurinol is used to inhibit xanthine oxidase to treat Gout

Question 5

Binding of substrate by the enzyme increases the _____ of the substrate.

Answer 5

effective concentration

Question 6

What are the two types of enzyme catalysis?

Answer 6

Acid-Base and covalent

Question 7

What does an amylase do?

Answer 7

Breaks down carbohydrates

Question 8

Digestive proteases are activated by?

Answer 8

Specific proteolytic cleavage

Question 9

Proteolytic digestive enzymes are synthesized as inactive precursors (________) that are activated after secretion

Answer 9

zymogens

Question 10

Is pancreatic lipase a zymogen?

Answer 10

No

Question 11

Are trypsin and chymotrypsin zymogens?

Answer 11

Yes

Question 12

What three amino acids make up the catalytic triad for proteolytic cleavage enzymes?

Answer 12

Asparate, Histidine, Serine

Question 13

What proteolytic cleavage enzyme activates chymotrypsin?

Answer 13

serine protease

Question 14

Reversible inhibitors interact with an enzyme via ______ associations while irreversible interact via _______ associations

Answer 14

noncovalent, covalent

Question 15

What are the three types of reversible inhibitors?

Answer 15

Competitive, Noncompetitive, uncompetitive

Question 16

A competitive inhibitor binds to?

Answer 16

The enzyme’s active site

Question 17

A noncompetitive inhibitor binds to?

Answer 17

Either the enzyme or the enzyme substrate complex

Question 18

An uncompetitive inhibitor binds only to?

Answer 18

The enzyme substrate complex

Question 19

A competitive inhibitor ______ Km and _______ Vmax

Answer 19

Increases Km but does not change Vmax

Question 20

What is the committed step for cholesterol synthesis?

Answer 20

The synthesis of mevalonate

Question 21

What enzyme synthesizes mevalonate and in turn is necessary for cholesterol synthesis?

Answer 21

HMG-CoA reductase

Question 22

What type of drugs are used to inhibit HMG-CoA reductase to decrease blood cholesterol?

Answer 22

Statins

Question 23

What type of inhibitors are statins?

Answer 23

competitive - they are shaped like mevalonate

Question 24

Nerve gas is what type of enzymatic inhibitor? what does it inhibit?

Answer 24

Irreversible

Acetylcholinesterase

Question 25

What are muscarinic acetylcholine receptors?

Answer 25

Main G-protein receptor complex in neurons of the PNS

Question 26

What activates muscarinic receptors of neurons?

Answer 26

Acetylcholine

Question 27

What enzyme metabolizes acetylcholine?

Answer 27

Acetylcholinesterase

Question 28

What happens if acetylcholinesterase is inhibited?

Answer 28

PNS problems, such as rigor mortis and paralysis

Question 29

What is the antidote for acetylcholinesterase inhibitors like nerve gas and parathion?

Answer 29

Atropine, it blocks access to muscarinic receptors

Question 30

Asprin is an irreversible inhibitor of what 2 enzymes?

Answer 30

COX-2 and COX-1

Question 31

Why does Asprin cause stomach problems?

Answer 31

COX-1 which it inhibits, is essential for stomach health

Question 32

What type of enzyme responds differently to different substrate concentrations?

Answer 32

Isozymes

Question 33

What two isozymes phosphorylate glucose?

Answer 33

Hexokinase (RBC) | Glucokinase (Liver)

Question 34

Which has a lower km hexokinase or glucokinase?

Answer 34

Hexokinase (RBC) has a low Km while glucokinase (liver) has a high Km. This ensures that RBCs get glucose when concentrations are low.

Question 35

What do Kinases do?

Answer 35

Add phosphate

Question 36

What do phosphatases do?

Answer 36

Removes phosphate

Question 37

What three amino acids can be phosphorylated?

Answer 37

serine, threonine, tyrosine

Question 38

What is the most common example of reversible covalent modification?

Answer 38

Phosphorylation/dephosphorylation of ser, thr, tyr

Question 39

What is the regulated enzyme of fatty acid synthesis?

Answer 39

Acetyl CoA carboxylase

Question 40

What is the end product of fatty acid synthesis and is also a feedback inhibitor of Acetyl CoA carboxylase?

Answer 40

Palmitoyl CoA

Question 41

Do allosteric enzymes obey Michaelis-Menten Kinetics?

Answer 41

No

Question 42

What does a allosteric enzyme substrate/reaction velocity curve look like?

Answer 42

Sigmoidal

Question 43

What is a key trait of allosteric enzymes?

Answer 43

They display cooperativity - activity of one functional site affects the activity at other sites

Question 44

What is Phosphofructokinase 1 (PFK1) activated by allosterically?

Answer 44

AMP