enzymes
Q1. What is an enzyme, and how does it speed up a chemical reaction?
Enzyme = globular protein that acts as a biological catalyst.
Speeds up reaction by lowering activation energy.
Forms enzyme–substrate complex at the active site.
Is not consumed in the reaction.
Q1. Name one enzyme used in a diagnostic test and state what it measures
Glucose oxidase (often with peroxidase).
Used in diabetes test strips.
Measures blood glucose concentration.
Which three enzyme classes are commonly used in chemical biocatalysis?
A: Hydrolases, oxidoreductases, lyases.
Which enzyme is used to produce lactose-free products?
A: Lactase
Q2. Explain why enzymes are described as specific to their substrates.
Enzymes have an active site with a specific shape.
Only the complementary substrate fits (lock-and-key / induced fit).
Ensures that each enzyme catalyses only one type of reaction.
Q2. How does streptokinase help treat patients after a heart attack?
Streptokinase activates plasminogen → plasmin.
Plasmin breaks down fibrin in blood clots.
Dissolves clot blocking coronary artery.
Restores blood flow to heart muscle.
What is the main advantage of using enzymes instead of inorganic catalysts in chemical synthesis?
A: High stereoselectivity and regioselectivity.
Name one enzyme in detergents and its stain target
A: Protease – protein stains.
Q3. A mutation changes the amino acid sequence of an enzyme’s active site. Predict and explain how this may affect the enzyme’s activity.
Alters the tertiary structure of the enzyme.
Active site no longer complementary to substrate.
Substrate cannot bind → enzyme–substrate complexes not formed.
Activity reduced or lost. (If mutation is conservative, enzyme may still function but less effectively.)
Q3. Explain how hyaluronidase improves the effectiveness of some injected drugs.
Hyaluronidase breaks down hyaluronic acid in connective tissue.
Increases tissue permeability.
Drug can diffuse more easily through tissues.
Improves absorption and delivery to target site.
Give one example of a chemical product made enantio-pure using enzymes.
A: Enantiopure alcohols, amines, or epoxides
Which enzyme is used in biodiesel production?
A: Lipase.
Q4. Why would life processes in cells proceed too slowly to sustain life without enzymes? Refer to activation energy.
Cellular reactions have high activation energy barriers.
At normal cell temperatures, reactions would occur too slowly.
Enzymes lower activation energy → allow reactions to proceed at rates sufficient for life.
Q4. Glucose oxidase is used in diabetes test strips. Suggest why this enzyme must be highly specific, and what might happen if it also reacted with other sugars in the blood.
Must be specific to glucose only.
If enzyme also acted on fructose / galactose, readings would be false/high.
Leads to incorrect diagnosis or treatment.
Why are enzymes considered part of “green chemistry”?
A: They avoid strong acids, bases, heavy metals, and toxic solvents
What role do cellulases play in the textile industry?
A: Bio-polishing fabrics to increase softness and reduce pilling.
Q5. PKU is caused by a deficiency of phenylalanine hydroxylase. Suggest how this deficiency leads to symptoms and how enzyme replacement therapy might help.
Phenylalanine not converted to tyrosine.
Phenylalanine accumulates → toxic to nervous system / brain.
Leads to developmental problems (e.g. learning difficulties).
Enzyme replacement therapy: provides functional enzyme to catalyse reaction.
Restores normal metabolic pathway and reduces toxic build-up.
Q5. Discuss the advantages and disadvantages of using enzymes in medical treatments and diagnostics, with reference to at least two named examples.
Advantages:
High specificity (glucose oxidase → accurate glucose test).
Can catalyse reactions under mild conditions (streptokinase dissolves clots without surgery).
Reduce need for invasive treatments.
Disadvantages:
Expensive to produce/purify.
May cause allergic reactions / immune response (streptokinase is bacterial).
Denatured by heat or pH changes.
Limited shelf life in some forms.
Examples to include: glucose oxidase, streptokinase, hyaluronidase, asparaginase, DNase.
Which engineered enzyme family is used for selective hydroxylation of hydrocarbons?
A: P450 monooxygenases.
Which enzyme type can degrade plastics like PET?
A: PET hydrolases.