Enzymes Flashcards
Alkaline Phosphates
Removes or hydrolyses phosphate groups. Often use in lab experiments to cleave phosphates and produce a colour change.
Definitions
Abzyme - an antibody with catalytic activity
Isoenzyme - two or more enzymes with different amino acid structure that catalyse the same reaction
Proteolytic enzymes
- 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
What is an enzyme ?
An enzyme is a protein that catalyses a specific chemical reaction in a living organism
What is chymotrypsin ?
- 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
Co-factors and activators
Enzymes often require a cofactor for activity :
- inorganic molecule
- organic molecule
Enzyme Kinetics
- 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
Michaelis-Menten derivation
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
Enzyme Activity
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.