Enzymes Are Proteins Flashcards
What must occur for an enzyme to catalyse a reaction
Must have complementary active site
Must come in physical contact with substrate
What are the two ways of measuring ROR
Product formed
Disappearance of reactants
Explain how enzymes catalyse reactions using induced fit model
Active site is roughly complementary to substrate
Presence of substrate cause change to tertiary structure causing induced fit, completely complementary now.
Active site is flexible
Explain how enzymes lower activation energy
Place strain on bonds holding substrate together when fit is induced
Bonds weaken so less energy is needed to break them.
What are the advantages of the induced fit model?
Explains lower AE
Explains how non-competitive inhibitors effect enzyme action.
How did the induced fit model come about?
Observations of non-competitive inhibitors altering enzyme activity.
Lock and key model can’t explain observations. Suggests active site is flexible not rigid
Explain the lock and key model
Suggests enzyme and substrate fit like a lock and key
Active site is rigid
Disadvantages of lock and key model
Doesn’t explain effect of non-competitive inhibitors
Or lowering of AE
What is the functional region of an enzyme?
+ when does it become functional?
The induced fit shape of the active site
Caused by change in environment (presence of substrate)
Define free energy
Energy available to do work
What are the conditions required for the catalysis of a reaction?
Complementary active site and substrate
Present activation energy
Physical contact between enzyme active site and substrate
How do you prove enzymes are proteins?
Use biuret reagent
Why are enzymes vital for life?
Allow metabolic reactions to occur fast enough for life
What is the tertiary of a enzyme like?
Globular
Most globular proteins have metabolic functions
What are enzymes also know as?
+ why?
Biological catalysts
Because: Made naturally (by body) and catalyses biological reactions
Why are enzymes effective at low conc. / doses?
Not used up, can catalyse infinite amounts of reactions
Describe non-competitive inhibitors
Inhibitors that bind to another binding site on an enzyme.
Doesn’t compete with substrate
Explain how non-competitive inhibitors work
They bond to other binding site other than active site.
Alters shape of active site making it no longer complementary to substrate.
No ES complex can form
Describe competitive inhibitors
Bind to active site as has similar shape to substrate. Forms enzyme inhibitor complex
Competes with substrate
Explain competitive inhibitors
Bind to active site, blocking substrate from binding. No ES complex can form.
What is an enzyme inhibitor?
A molecule that prevents ES complexes from forming
What are the two categories of enzyme inhibitors?
Temporary and permanent
Give examples of inhibitors
Poison and drugs
As enzyme conc doubles what happens to ror?
Doubles
What are hydrogen bonds in the secondary structure between?
C==o H——N
Involved in peptide bond
What groups are H bonds between in the tertiary structure?
OH O——C==O
What’s the difference between the h bonds in the secondary and tertiary structure?
2= atoms invoked in peptide bonds
3= atoms in r group
