Lecture 5: functions and kinetics

Question 1

Types of cofactors

Answer 1

1-inorganic: metal ions

2- organic: groups derived from vitamines

Question 2

acceleration of reactions catalysed by enzymes compared to non-catalysed

Answer 2

10^6 to 10^12 fold

Question 3

enzymes are complementary to ….

Answer 3

transition states

Question 4

catalytic mechanisms leading to enzyme functions

Answer 4

1- acid-base catalysis
2-covalent catalysis
3- metal ion
4- orientation based catalysis

Question 5

How can proton acceptor (general bases) contribute to base catalysis

Answer 5

they abstract a proton making the substrate a good nucleophile

Question 6

How can metal ions catalyse reactions in enzymes

Answer 6

1- In oxidation-reduction reactions
2-electronically shielding and stabilising negative charges
3- By providing the correct orientation

Question 7

which cofactor is used in carbonic anhydrase and what is the function?

Answer 7

zinc ions
zinc forces the water to release a proton.
The CO2 goes to the active site and the hydride attacks CO2 producing HCO3-

Question 8

What are the 6 classes of enzymes

Answer 8

1- oxidoreductases
2-transferases 
3-hydrolyaser
4-lyaser
5-isomeraser
6-ligaser

Question 9

oxidoreductases need…..

and often contain …. metal ions

Answer 9

Cofactors

Fe 3+/2+

Question 10

Which enzyme class kinases do kinases belong to

Answer 10

transferases

Question 11

Which catalytic mechanisms are used for peptide hydrolysis

Answer 11

covalent hydrolysis and acid-base catalysis

Question 12

The active site of chymotrypsins can accomodate which …. side chains

Answer 12

aromatic

Question 13

which enzyme class does adenylate cyklase belong to?

Answer 13

lyases

Question 14

enolase belongs to

Answer 14

lyases (hydratase; danner vand)

Question 15

Enzymer som fjerner carboxyl-grupper er…

Answer 15

lyases

Question 16

Assumptions made in michael mentens kinetics

Answer 16

The rate of complex degradation is not reversible

The rate of the formation of complex is the same as the rate of the formation of reactants from the complex

Question 17

The optimum pH of an enzyme is close to the pH of the …….in which the enzyme is found

Answer 17

environment