Enzymes Flashcards
What are enzymes
Proteins that act as biological catalysts for intra and extra cellular reactions to determine structure and function. Affects metabolism of cells and whole organism
Induced fit model of enzyme action
Shape of active site is not directly complementary to substrate and is flexible
Conformational change enables ES
complexes to form when substrate adsorbs
This puts strain on substrate bonds, lowering activation energy. Bonds in enzyme product complex are weak, so product desorbs
Explain lock and key model of enzyme action
Active site has rigid shape determined by tertiary structure so is only complementary to 1 substrate. Formation of ES complex lowers activation energy.
Bonds in enzyme product complex are weak so product desorbs
How does substrate concentration affect rate of reaction
If enzyme concentration is fixed, rate increases proportionally to substrate concentration
Rate levels off when maximum number of ES complexes form at any given time
How does enzyme concentration affect rate of reaction
Given that substrates is in excess, rate increases proportionally to enzyme concentration
Rate levels off when maximum number of ES complexes from at any given time
How does temperature affect the rate of enzyme controlled reactions
Rate increases as kinetic energy increases and peaks of optimum temperature
Active site no longer complementary to substrate (denaturation)
What is temperature coefficient
Q10 measures the change in rate of reaction in 10C temperature increase
Q10 = R2/R1 (where R represents rate)
How does pH affect rate of reaction
Enzymes have a narrow optimum pH range
Outside range = denaturation
