Enzymes

Question 1

Alkaline Phosphates

Answer 1

Removes or hydrolyses phosphate groups. Often use in lab experiments to cleave phosphates and produce a colour change.

Question 2

Definitions

Answer 2

Abzyme - an antibody with catalytic activity

Isoenzyme - two or more enzymes with different amino acid structure that catalyse the same reaction

Question 3

Proteolytic enzymes

Answer 3

• Papain - generalist enzyme - from papaya plants and used in the meat tenderising industry
• Trypsin - specific -peptide bond cleavage - only on the carboxyl side of lysine and arginine residues

-Thrombin - blood clotting - catalyses the breaking of arginine/glycine bonds but only within particular peptide sequences

Question 4

What is an enzyme ?

Answer 4

An enzyme is a protein that catalyses a specific chemical reaction in a living organism

Question 5

What is chymotrypsin ?

Answer 5

• made in the pancreas and works in the small intestine to specifically break down dietary proteins
• the cleft in the enzyme contains the active site near. the side chains of three residues
• chymotrypsin = catalyses the hydrolysis of peptide bonds at a rate of 190 per second
• carbonic anhydrase = catalyses the hydration of CO2 from tissues to the blood system to alveolar air

Question 6

Co-factors and activators

Answer 6

Enzymes often require a cofactor for activity :
- inorganic molecule
- organic molecule

Question 7

Enzyme Kinetics

Answer 7

• The kinetic of an enzyme are measure on the basis of the substrate concentration.
• Michaelis menten - describe enzyme activity and measure it in terms of S

Question 8

Michaelis-Menten derivation

Answer 8

this derivation is based upon the assumption that one molecule of substrate combines with one molecule of enzyme to form the E-S complex ; if substrate is in excess and therefore the amount combined in ES is negligible, the VMax is reached

Question 9

Enzyme Activity

Answer 9

Activity is simply the rate of the reaction measure in terms of mass of substrate converted per unit time.

Specific activity - is a measure of purity.

An enzyme unit is the amount of enzyme that will catalyse the conversion of q micromol of substrate in 1 min.