Enzyme catalytic strategies

Question 1

2 things that enzyme activity depend on?

Answer 1

pH
Temperature

Question 2

How does increase in temp affect enzyme activity?

Answer 2

Increases it as molecules move faster

Question 3

4 catalytic principles used by enzymes

Answer 3

Covalent catalysis
General acid-base catalysis
Catalysis by approximation
Metal ion catalysis

Question 4

Which catalytic strategies does chymotrypsin combine?

Answer 4

Covalent, acid-base and transition-state

Question 5

What does protease catalyse?

Answer 5

Proteolysis
Cuts down proteins

Question 6

Difference between nucleophile and electrophile

Answer 6

Nucleophile: Accepts protons and donates electrons
Electrophile: Donates protons and accept electrons

Question 7

What is chymotrypsin involved in?

Answer 7

Breaking down proteins into small peptides by cutting a specific location on peptide backbone

Question 8

What is the catalytic triad?

Answer 8

Serine, Histadine and Asperegine
They have to be close in the folding

Question 9

Where does the cutting occur in chymotrypsin?

Answer 9

In the hydrophobic pocket, the serine cuts the protein when it is attached to the hydrophobic pocket

Question 10

What does the oxyanion hole do?

Answer 10

Protects the enzyme

Question 11

Does the S1/hydrophobic pocket differ in protease?

Answer 11

Yes

Question 12

Do proteases cut in only one point?

Answer 12

Yes

Question 13

What allows for the specificity in proteases?

Answer 13

The difference in hydrophobic pockets

Question 14

Example of aspartyl protease

Answer 14

Pepsine

Question 15

What is site-directed mutagenesis?

Answer 15

Replace one amino acid with another
Example how the catalytic triad was discovered

Question 16

3 classes of proteases

Answer 16

Cysteine
Aspartyl
Metalloproteases

Question 17

Which amino acid is conservative replacement (keep good activity) in serine?

Answer 17

Cystine

Question 18

What is indinavir?

Answer 18

Analogue of the substrate

Question 19

What does carbonic anhydrase do?

Answer 19

Make a fast reaction faster
Helps with metabolism

Question 20

How many carbonic anhydrasases (esoenzymes) in the body?

Answer 20

7

Question 21

What is the Kcat?

Answer 21

Enzyme turn-over number
Amount of product produced per unit of time per enzyme

Question 22

How does pH effect carbonic anhydrase activity?

Answer 22

Reaction is higher (Kcat) in basic environment because a group that loses a proton plays an important role in the activity of carbonic anhydrase

Question 23

Which was the first enzyme that uses a metal that was discovered?

Answer 23

Carbonic anhydrase

Question 24

What is lysozyme?

Answer 24

An antibacterial enzyme

Question 25

What does lysozyme attack?

Answer 25

Peptidoglycan

Question 26

What is peptidoglycan?

Answer 26

Polysaccharide found in many bacterial cell walls

Question 27

Example of where lysozyme I found?

Answer 27

In the numerous body fluid (blood, sweat, saliva, sweat, tears, urine)

Question 28

What are isoenzymes?

Answer 28

Enzyme variants that are the product of different genes and thus represent

Question 29

What are allozymes?

Answer 29

different loci Enzymes that are the product of different alleles of the same gene

Question 30

Why are isoenzymes clinically relevant?

Answer 30

Helps determine where the enzymes in the tissue are coming from. This helps determine if there are for example liver damage (if there are liver enzymes present in the blood)

Question 31

How can heart attacks be found out with the help of isoenzymes?

Answer 31

If heart enzymes are found in the blood when isoenzymes are separated by electrophoresis there can be a sign of heart attack

Question 32

How are different isoenzymes identified?

Answer 32

Electrophoresis (because of charge and size)

Question 33

What is the same in isoenzymes?

Answer 33

The active site

Question 34

What kind of enzyme class do proteases belong to?

Answer 34

Hydrolase

Question 35

Can a nonbiological catalyst produce more than one product with the occurrence of side reactions?

Answer 35

Yes

Question 36

Must a substrate bind to the active site before catalysis can occur?

Answer 36

Yes

Question 37

Do enzymes change the free energy of a reaction?

Answer 37

No

Question 38

What is the optimal temperature for enzyme activity?

Answer 38

35-45c

Question 39

Is the optimal pH the same for all enzymes?

Answer 39

No it very much depends on the enzyme and its function and where its found

Question 40

What is covalent catalysis?

Answer 40

Active site contains a nucleophile that is briefly covalently modified

Question 41

What is general acid-base catalysis?

Answer 41

A molecule other than water donates or accepts a proton

Question 42

What is catalysis by approximation?

Answer 42

A molecule other than water donates or accepts a proton

Question 43

What is metal ion catalysis?

Answer 43

Can function in different ways Example: electrophilic catalyst

Question 44

What does the hydrophobic pocket recognise?

Answer 44

Peptide bonds

Question 45

Why does apartyl protease work best in acidic conditions?

Answer 45

Because it can be protenated

Question 46

Serine, histamine and superfine in the catalytic triad are not close when looking at the primary structure, how do they make up the catlytic triad?

Answer 46

They are close in the tertiary structure thanks to the folding

Question 47

What in chymotrypsin catalyses the cleavage of peptide bonds ?

Answer 47

The catalytic triad

Question 48

What explains substrate specificity of trypsin, chymotrypsin and elastase?

Answer 48

Structual difference in the binding site

Question 49

What is the rocket in chymotrypsin, polar or nonpolar?

Answer 49

Nonpolar

Question 50

How does the pocket of trypsin differ from that of chymotrypsin?

Answer 50

It has Asp instead of Ser

Question 51

How does elastase differ from chymotrypsin?

Answer 51

There are no pockets present

Question 52

Why are there no pockets in elastase?

Answer 52

Because 2 glycerine is replaced by Val and Thr

Question 53

What does the hydrophobic pocket of chymotrypsin bind?

Answer 53

Aromatic amino acids

Question 54

Is chymotrypsin hydrophobic or hydrophilic?

Answer 54

Hydrophobic

Question 55

Why does the group have to be protected to work better in aspartyl proteases?

Answer 55

Because the conditions have to be acidic

Question 56

What is pepsin?

Answer 56

An aspartyl protease

Question 57

How do metalloproteases work?

Answer 57

The peptide carbonyl group is attacked by a metal-activated water molecule

Question 58

What carbonic anhydrase used to do in animals?

Answer 58

Transport CO2 out of muscles and maintain blood pH balance

Question 59

What catalyses the reaction of hydration CO2 to form bicarbonate?

Answer 59

Carbonic anhydrase

Question 60

Which ion is found at the active site of carbonic anhydrase?

Answer 60

Zinc ion

Question 61

What does catalysis with carbonic anhydrase entail?

Answer 61

Zinc activation of a water molecule

Question 62

What does zinc ion promote the ionisation of? and what does it result in

Answer 62

Bound H2O, resulting nucleophilic OH- attacks carbon of CO2

Question 63

Why does the zinc in carbonic anhydrase make the reaction much faster?

Answer 63

Because water without zinc is a very weak acid/nucleophile

Question 64

What is peptidoglycan?

Answer 64

A polysaccharide found in many bacterial cell walls

Question 65

What does the cleavage of the cell wall of bacteria lead to?

Answer 65

Lysis of bacteria

Question 66

Antibacterial enzyme

Answer 66

Lysozyme

Question 67

When is lysozyme released into the blood stream?

Answer 67

When granulocytes and monocytes are released

Question 68

What does lactate dehydrogenase catalyse?

Answer 68

A step in anaerobic glucose metabolism and glucose synthesis

Question 69

What does LDH stand for?

Answer 69

Lactate dehydrogenase

Question 70

Why can isozymes be exerted by electrophoresis?

Answer 70

Because they differ slightly in charge