Enzymes and active site Flashcards
What does the lock and key model show?
-Substrate is complimentary to the active site of the enzyme
-Active site doesn’t change and fits the substrate like a key in a lock
-Produces get made and active site is the same
What does the induced fit model show?
-Substrate colliding with the active site
-Active site changes shape to fit the substrate in, holds in position by opposite charged groups in animo acids in active site
-Enzyme-substrate is formed
-A change in active site shape puts strain on substrate/ brings two closer, reaction energy decreases
-Enzyme-product is formed
-Product released as no longer fits
-Active site changes to og shape
What is an intercellular and an extracellular enzyme?
Intercellular- Work inside cell
Extracellular- Secreted outside of cell
What is the structure and type of molecule of an enzyme?
-A globular 3D protein (tertiary structure)
-Very specific, catalyse only one substrate
-Active site has a complimentary shape to the substrate
What is made when a substrate fits into the active site?
Enzyme-substrate complex
Catabolic reaction?
Hydrolysis larger into smaller molecules
Anabolic reactions?
Larger molecules made by condensation of smaller ones
What is an enzymes turnover number?
No. of substrate to products per unit of time
How does slight and extreme difference from optimum pH do to an enzyme?
Slight- OH-/H+ ions intervene with the ionic bonds of the r group of amino acids causing temporary reversible changes to the 3d globular tertiary structure
Extreme- OH-/H+ ions break ionic bonds and permanent changes to the tertiary 3d structure, enzyme becomes denatured eventually
What are immobilised enzymes?
Enzymes that are attached to an inert, insoluble material
What are the advantages of using an immobilised enzyme?
-Can be reused, reduced costs
-Product can’t be contaminated by enzyme
-Easy to recover and add
-Stable at high temperatures and wide range of pH
What are the disadvantages of using immobilised enzymes?
-More expensive than free enzymes
-Immobilisation can change the shape of the active site, meaning les s-e complexes are formed
Ways an enzyme can be immobilised?
In gel membrane, in alginate beads
What happens when an enzyme is working at its optimum pH?
-Charges and shape complementary
-Working at max. turnover rate
-Max no. of e-s complexes formed and amount of substrate broken down
