Enzymes Flashcards
(15 cards)
Types of enzymes
Intracellular- work inside cells eg catalase
Extracellular- work outside cells eg amylase
Enzymes
Biological catalysts
Globular proteins
Specific active site shape
Reduce activation energy
Lock and key
Substrate fits perfectly in active site
Forming enzyme-substrate complex
Induced fit
As substrate binds to active site
Active site changes shape to fit substrate more closely
Bonds formed with enzyme weaken bonds in substrate to encourage splitting into products
Temperature
Rise in temperature causes enzyme mol3cules to vibrate more
Above optimum temperature, vibrations can change active site shape
No longer fits substrate
Initially, as temperature increases rate increases due to increased kinetic energy
Q10- rate at high temperature ÷ rate at low temperature
Ph
Different enzymes have different optimum pH
Above or below optimum imbalance of H+ and OH- ions interact with ionic and hydrogen bonds in tertiary structure which changes the shape of the active site so enzyme denatures
Enzyme concentration
More enzymes available means more complexes can form increase rate
Reaction rate slows once substrate becomes limiting
Substrate concentration
Higher concentration high3r rate
More collisions and more complexes form
Increases until saturation, all active sites used up
Initial rate is fastest2
Cofactors
Non protein groups attached to enzymes to activate them
Inorganic molecules- help enzyme and substrate bind together, aren’t used up or changed (cl- in amylase)
Organic molecules (coenzymes)- participate in reaction continually recycled (vitamins)
Prosthetic group- tightly bound to enzyme, permanent part of active site ( Zn2+ in carbonic anhydrase)
Competitive inhibition
Similar shape to substrate
Comp3te with substrate for active site
Block active site
Depends on relative concentrations
Higher concentration of substrate reverses effect
Non competitive inhibitors
Bind to allosteric site which changes shape of active site
Substrate no longer can binds
Not affected by substrate concentration
Reversible and non reversible inhibition
Revereible- weak hydrogen bonds/ ionic bonds
Non reversible- strong covalent bonds
End product inhibition
Metabollic pathway ( series of connectedmetabollic reactions)
Enzymes inhibited by product produced further on in pathway
Controls and regulates product quantity
Reversible, so when levels drop, they start to rise again
