2.1.4 Enzymes Flashcards
Enzyme action
Catalysts
Growth=anabolic
Breakdown=catabolic
Lock and key hypothesis
Active site, enzyme-substrate complex, enzyme-product complex
Induced fit hypothesis
Active site changes shale slightly as substrate enters
Initial interaction between enzyme and substrate = weak
Rapidly induces a change in the enzymes tertiary structure
Binding puts stress on the substrate weakening bonds
Lower Ea of reation
Intercellular enzymes
Act within cells
e.g. toxic products of metabolism by catalase —> O2 and H2O
Extracellular enzymes
Released from cells to break down large nutrient molecules to smaller ones during digestion
Digestion of starch
Amylose
Maltose
Digestion of proteins
Protease
Effect of temp on enzyme activity
Q10 measures how mum ROR increases with a 10 degree rise
Optimum temp = highest ROR
Past this = denatured
Effect of pH on enzyme activity
Change in H+ concentration results in change in structure of enzyme/active site
Will renature is pH returns to normal
Effect of conc on enzyme activity
Increases the number of successful collisions so ROR increases
Will reach Vmax when rate can’t increase any further
Competitive enzyme inhibitors
Similar shape to substrate, blocks it from entering
Enzyme can’t carry out function = inhibited
Slows ROR
Non-competitive enzyme inhibitors
Binds to allosteric site
Changes tertiary shape of enzyme so active site no longer complementary
Decreases ROR
End product inhibition
When the product of a reaction acts as an inhibitor to the enzyme that produces it
Negative feedback control mechanism
Non-competitive reversible reaction
Cofactors
Non-protein ‘helper’
From diet
Coenzyme
Organic cofactor
From vitamins
