Lecture 2 - Enzyme Catalysis

Question 1

Where does the nature and specificity of enzymes come from?

Answer 1

3D structure of folded protein

Question 2

Activity of an enzyme may be regulated by what molecules?

Answer 2

Co factors and co enzymes

Co factors are inorganic
Co enzymes are organic

Question 3

List some common types of enzyme (7)

Answer 3

Hydrolyses: catalyse a hydrolytic cleavage reaction

Nucleases: break down nucleic acids

Proteases: break down proteins

Synthases: condense two smaller molecules together

Isomerases: Rearrange bonds in a molecule

Kinases: add phosphate groups to molecules

Phosphatases: remove phosphate groups

Question 4

Give some applications of hydrolases (5)

Answer 4

Penicillin acylase: production of semi-synthetic penicillins from penicillin G

Lactase: removal of lactose from whey, milk

Isoamylase: production of maltose from starch

Keratinase: modification of wool, hair, leather

Tannase: removal of tannic acid from foods

Question 5

Define specific activity

Answer 5

Enzyme concentrations are given in units of specific activity.

This is the amount of enzyme by mass or mole, which gives a certain amount of catalytic activity under specified conditions

Specific activity = activity/mg protein

Question 6

Write the standard equation for Michaelis Menten kinetics

Answer 6

E + S = ES + P

Question 7

What is the rate of product formation according to Michaelis Menten Kinetics

Answer 7

V = dP/dt = k2ES

Question 8

Derive the Michaelis Menten rate equation

Answer 8

Refer to notes

Question 9

Linearise the Michaelis Menten equation to produce three separate equations. Name them and state benefits

Answer 9

Refer to notes

Question 10

From a plot of v against s explain how you would find vmax and Km

Answer 10

When (S) is much larger than Km, the reaction rate will be at vmax found by drawing horizontal line to the y axis

When (s = km) v = 1/2 vmax and therefore drawing (s) from the value of vmax/2 is equal to km