Biol 1 - Enzymes

• A biological catalyst
• Protein
• Active Site has specific shape so highly specific 

Reduces activation energy needed for a reaction

• If joining, holding two substrates close together reduces repulsion
• In breakdown (lysis) fitting to active site puts strain on bonds 

Lock & Key Model:

• No longer so widely accepted
• Says substrate fits enzymes active site like a key to a lock

Induced Fit Model:

• Substrate doesn't just need complementary shape - needs to induce enzyme to change active site shape
• So substrate is locked more tightly
• More accepted theory - explains why so specific

Temperature:

• More heat = more kinetic energy, so reaction speeds up (more collisions)
• To a point - temp too high can denature the enzyme 

pH:

• Optimum pH (usually 7)
• Above and below H and OH ions can interfer with ionic hydrogen bonds and denature enzyme

Substrate concentration:

• Higher substrate conc.= faster reactions (more collisions)
• Up to a saturation point