Biocatalysis 1

Question 1

Name 4 general uses of biocatalysts?

Answer 1

Uses of whole cells to make products - beer/bread
Product of asymmetric product - drugs (chirality)
Large scale production - high fructose corn syrup
Enzyme is the final product - washing powder

Question 2

What are the advantages of biocatalysts?

Answer 2

• Chiral Chemistry
• Specificity (few side products)
• Gentle conditions required (Aqueous, ambient ~27˚C)
• Recombinants allows large scale production

Question 3

What are the disadvantages of biocatalysts?

Answer 3

• Low tolerance to certain conditions
• Inhibition in long metabolic pathways as feedback mechanisms (protein engineering can remove this)
• Limited to reactions that are ‘useful for life’

Question 4

How many numbers are in an E.C number?

Answer 4

4

Question 5

What does it mean if an E.C number is exactly the same?

Answer 5

It catalyses the same number (may be from a different species)

Question 6

Group Classification is a hydrolase?

Answer 6

3

Question 7

What percentage of enzymes in industry are hydrolases?

Answer 7

70%

Question 8

What is DERA used for?

Answer 8

Enantioselective synthesis of cholesterol lowering drugs (statins)
Catalyses the addition of two aldol groups

Question 9

How many chiral centres are in the constant region of the statin drugs (e.g. atorvastinin)

Answer 9

2

Question 10

What percent of people in the developed world use statin at some point in there life?

Answer 10

80%

Question 11

What is the enzyme blocked by statins?

Answer 11

HMG Co-A reductase

Question 12

The constant region of statins has two chiral centre. Why is important?

Answer 12

If produced non-biologically only 25% of products would be functional statins

Question 13

What classification group is DERA in?

Answer 13

Group 2 - transferase

Question 14

Which classification of enzymes are involved in the production of high fructose corn syrup?

Answer 14

3 (hydrolase) and 5 (isomerase)

Question 15

Corn starch comes as a slurry. What does this mean?

Answer 15

Partially solid, not dissolved

Question 16

What happens in the liquidification step of HFCS production?

Answer 16

alpha-amylase breaks starch down to 10-13 sugar units

Question 17

What conditions are required for functional alpha-amylase?

Answer 17

pH 6-6.2 and calcium ions

Can be performed at high temp (105˚)

Question 18

What occurs in the saccharify step?

Answer 18

Glucoamylase breaks the starch in glucose monomers

Question 19

What conditions are required for functional Glucoamylase?

Answer 19

pH 4.2-4.5

Question 20

What occurs in the isomerisation step?

Answer 20

glucose isomerase converts the mixture to 50% glucose and 50% fructose.
Fructose is removed at 42% (not run to equilibrium) using chromatography to produce a high fructose stream and the glucose is put back into the isomerisation reaction.

Question 21

What conditions are required for functional glucose isomerase?

Answer 21

pH 7.8

Question 22

What is the purpose of (dynamic)/kinetic resolution?

Answer 22

To remove the undesired enantiomer using the selectivity of an enzyme

Question 23

What is kinetic resolution?

Answer 23

Principle is that the enzyme can only add groups to one enantiomer (the desired enantiomer).
OR
Enzyme is destroy (hydrolyse) only one enantiomer

Question 24

What is the limitation with kinetic resolution?

Answer 24

Production is capped at 50%.

Question 25

What is dynamic kinetic resolution?

Answer 25

First enzyme is an isomerase which interconverts one enantiomer to another (to reach a 50% equilibrium)
The second adds a group to the desire product so it cant be back converted and removed
Theoretically you get 100% yield