ENZYMES
Enzyme - Biological catalyst which is protein in nature. Speeds up rate of reaction without being used up in the reaction itself. Lowers activation energy by providing alternate pathway for reaction to occur.
Active site is the polar region of the amino acid in the enzyme.
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Substrate - Reactant in a biochemical reaction.
Active site - Region on the surface of an enzyme to which substrates bind and which catalyses the reaction.
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Activation energy - Amount of energy required for a reaction to start.
Figure 1. Enzyme (Robinson, 2015)
Induced-Fit Model
- As substrate approaches enzyme, it induces a conformational change in the active site.
- Conformational change stresses the substrate, reducing activation energy of reaction
Denaturation - Changing the structure of an enzyme so that it cannot carry out its functions.
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Denaturation of enzymes occurs due to:
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High temperatures
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Change in pH
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Denaturation is an irreversible change.
FACTORS AFFECTING ENZYME ACTIVITY:
- Temperature
- pH
- Substrate concentration
- Enzyme concentration
LACTOSE INTOLERANCE
Happens when the body doesn't produce lactase. Different alternatives for taking lactose containing foods/beverages are:
- Lactose supplements taken regularly
- Drink lactose free milk
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Lactose free milk can be created through two methods.
1) Add lactase to milk (low quality milk, waste of lactase)
2) Run milk through apparatus with lactase enzyme using alginate beads.
Metabolic Pathways - Chains or cycles of enzyme-catalysed reactions. The product of one reaction is the reactant of the next.
e.g. bloodclotting, Krebs cycle (cell respiration), Calvin cycle (photosynthesis).
cell damage
clotting factors
thrombin
fibrinogen (soluble)
fibrin (insoluble)
captures erythrocytes
clot
BLOOD CLOTTING
Inhibition of Enzymes
- Competitive or non-competitive
- An inhibitor fits into an allosteric site causing a conformational change in the active site so substrate cannot fit in non-competitive inhibition
- Inhibitor fits the active site and prevents the substrate from entering in competitive inhibition
For a more basic understanding of enzymes, with detail on basic concepts click here.