Bio - Enzymes I

What is a barrier for spontaneous reactions from taking place

activation energy

Why is heat not used instead of enzymes

Hard to control heat
Too much heat causes denaturation
Enzymes are specific

How do enzymes lower Ea

Brings molecules closer together for more collisions
Bends and stresses bonds
Phosphorylation of enzymes changes its shape so more bends
Stabilizes transition state, less energy needed

What do enzymes do

Increase rate of reaction
Lowers Ea
Do not get consumed
Does not change reaction
Does not change spontaneity

Enzyme substrate complex

Temporary structure when substrate is binded to enzyme

Active site

The region on a enzyme where substrate binds and reactions take place

Lock and key theory

Outdated model of enzyme and substrate
Enzyme can only bind to a specific substrate and only that
Active site is a rigid site

How does lock and key theory help our current understanding of enzymes

Explains specificity for enzymes
Loss of activity when enzymes denature

Co-factor

Non protein helper that some enzymes need to function properly
Helps enzymes function properly
Activates enzyme
Acts as a carrier
Can be inorganic or organic

Where do reactions find energy after enzymes lower Ea

Collisions give kinetic energy

What are the 2 co factors and what do they do

Inorganic cofactors - Metal ions (charged particles), helps stabilize and bind substrate
Organic cofactors - Co-enzymes, often vitamins, helps transfer electrons
All co enzymes are co factors, not the other way around

Induced fit theory

Enzymes active site is flexible, not rigid
R groups of enzyme form intermolecular interactions with substrate, changing the shape of the enzyme to fit substrate
H2O is added to enzyme substrate complex to break bond
Describes behavior of different enzymes
Substrate specificity is determined by properties and arrangements of AA functional groups

Organic meaning

A compound has carbon in it (usually H too)

Factors affecting enzymes

Substrate concentration - more substrate=more collisions, eventual plateau when enzymes are full (saturation point)
Temperature - too hot and enzymes denature, ideal temp for most enzymes is 30 C
pH - Extreme levels cause denaturation
Inhibitors