U1- Topic 4: Proteins & Enzymes Flashcards
Peptide
polymer of amino acids (smaller)
Polypeptide
Peptide of many amino acids (longer)
Proteins
Polypeptide that is folded into a complex 3D shape
Primary 1*
Linear sequence of amino acids
-everything starts from primary structure
“Structure determines function”
Secondary 2*
formation of helices and sheets due to H-bonds in “backbone”
Helices - more common secondary structure. h-bonding in backbone of amino acids NEAR each other in linear sequence
Sheet - h-bonding in backbone of amino acids FAR from each other in linear sequence
Tertiary 3*
“folded” 3D shape of protein
Quaternary 4*
arrangement of multiple polypeptide chains into a 3D arrangement
Enzymes
Special type of protein responsible for catalyzing reactions (not consumed in rxn)
- decrease activation energy
- can be used over and over again
Ways to Speed Up Chemical Reactions
Increase concentration of reactants
Increase temperature
Add catalyst
Enzyme as Coupling Device
Many enzymes catalyze multiple reactions at the same time, usually necessary when free energy of desired rxn is positive
Enzymes can couple a very favourable rxn with an unfavourable rxn to make the overall rxn spontaneous
Competitive Inhibitors
Chemically similar to the substrate
Binds to enzyme at the active site, COMPETES with substrate for binding
Molecule with highest concentration will OUT COMPETE the other
Does not affect Vmax
Reduced affinity for substrate, increased Km
Non-competitive Inhibitors
Not chemically similar to substrate
Binds at allosteric site, different from active site
- changes the shape of active site
Does not affect Km, lowers Vmax
Allosteric Activators
Bind to enzyme, which will change shape of enzyme to a MORE active form
Allosteric Inhibitor
Bind to enzyme, which will change shape of enzyme to a LESS active form
Feedback Inhibition
Final product of a pathway inhibits an enzyme earlier in the pathway
