Enzymes Flashcards
What are enzymes?
biological catalysts- speed up the rate of metabolic reactions but are unaltered by those reactions so reusable
What type of proteins are enzymes?
globular
How do enzymes act as catalysts?
enzyme combines with substrate to form enzyme-substrate complex
thereby lowering the activation energy
What is activation energy?
the energy required for a reaction to proceed
Why is lowering the activation energy useful?
it allows chemical reactions to proceed at body temperature
What is the part of an enzyme that the substrate combines with?
the active site
How many active sites could each enzyme have up to?
30
Typically how many amino acids residues does the active site consist of?
3 to 12
What is enzyme specificity?
the shape of the active site is complementary to the shape of the substrate (exact fit), thus the substrate fits into the active site to form an enzyme substrate complex
What us the lock and key mechanism?
substrate fits exactly into the active site of the enzyme, no other types of substrate will fit it
What is the induced fit mechanism?
When the substrate binds to the active site, it induces a conformational change in the enzyme (enzyme changes to fit with substrate better)
What do oxidoreductases do?
catalyse oxidation and reduction reactions
What do hydrolases do?
catalyse hydrolysis reactions
How does temperature affect the rate of an enzyme controlled reaction?
an enzyme works best at a certain temperature this is the optimum temperature
before this temperature a enzyme works at a lesser rate
after this temperature the enzyme begins to denature and so will work at a lesser rate and steeply fall off to not at all
How does pH affect the rate of an enzyme controlled reaction?
enzyme works best at a certain pH, optimum pH
slight variations from this pH the enzyme will work at a slightly lesser rate, the further alkaline/acidic the pH goes the enzyme will denature until it does not catalyse the reaction at all
What happens as substrate concentration increases?
there are more successful random collisions between the enzyme and the substrate and the rate of reaction increases
What is a limiting factor as substrate concentration increases?
enzyme concentration
What happens as enzyme concentration increases?
there are more active sites to enable more enzyme-substrate complexes to be formed and the rate of reaction increases
What is a limiting factor as enzyme concentration increases?
substrate concentration
What is competitive inhibition?
when an inhibitor interferes with active site of enzyme by binding to it, so the substrate cannot bind
What is non-competitive inhibition?
when an inhibitor binds to an allosteric site of an enzyme, and this changes the shape of the enzyme so the substrate cannot bind to it
What is enzyme technology
enzymes extracted and purified from microorganisms
such enzymes are used in extensively in industry, medicine and food technology
over 2000 enzymes have been identified: of these over 150 are used in industrial processes
Why are enzymes useful in technology?
they are catalysts (speed up reactions)
can be re-used
they are specific, therefore act on specific substrates and produce specific products
factors which affect their activity can be easily controlled
they are biodegradable, environmentally friendly
they can be immobilised (adherence onto the surface of inert material by adsorption)
