Enzymes + HL Enzymes

Enzyme

a biological catalyst made of protein

Catalyst

a substance that speeds up a chemical reaction without being used up in the reaction

Catabolic reaction

large molecules are broken down into smaller molecules, releasing energy
ag digestion, amylase converts starch into maltose

Anabolic reaction

small molecules are joined together to form large molecules, using energy
DNA polymerase forms and repairs DNA

Structure of enzymes

• each enzyme has its own unique shape, and will only react with one type of substrate
• the protein of the enzyme is folded into this 3d shape
• the area of the enzyme that reacts with the substrate is called the active site

What is the induced fit theory?

the shape of the active site is induced, meaning it changes shape slightly to make the substrate fit better

What is the enzyme substrate complex

enzyme bonded to substrate

What is the result of enzyme action?

• new product released
• enzyme released is unchanged and can be reused

How does pH affect enzyme action?

• changes the shape of the active site, hence affecting how well the enzyme works
• optimum pH varies depending on the enzyme

How does temperature affect enzyme action?

• as temperature increases, the rate of reaction increases
• optimum temp for human enzymes 37 degrees celcius
• optimum temp for plant enzymes 20-30 degrees celcius
• above optimum temperature, enzymes become denatured

Denatured enzyme

permanent change in the shape of the active site of an enzyme and can no longer function, irreversible damage
caused by both incorrect pH and high temperatures

Inhibitors

attach to enzymes and destroy their shape, effectively denaturing the enzymes

Example of beneficial inhibitors

• insecticides affect enzymes in insects causing their death
• drugs can affect enzymes involved in pain, causing the pain to stop

Harmful inhibitors

• nerve gases used by terrorists attach to the enzymes involved in our nervous system
• cyanide denautres an enzyme involved in our respiratory system

Bio-processing

the use of enzyme controlled reactions to produce a product

Bioreactor

a vessel or container in which living cells of their products are used to make a product

Immobilised enzymes

enzymes that are attached to each other, or an inert material and can easily be reused

Physical methods of immobolising enzymes

adsorption- enzymes are physically attached to inactive supports such as glass beads or ceramics

adsorption to ceramics
enclosed by a membrane
enclosed in a gel

Chemical methods of immobilising enzymes

bonded to inert support
bonded to each other

Advantages of immobilised enzymes

• efficiency of enzymes is not affected
• can be easily recovered from the product so you can get a pure sample easily
• enzymes can be reused, which also cuts costs
• often more stable when immobilised

Uses of immobilised enzymes

• penicillin acylase changes the structure of penicillin to make more antibiotics that will fight a wider range of bacteria
• lactase converts lactose into sweeter sugars glucose and galactose which are then used by food manufacturers

What is the enzyme immobilised in the experiment?

sucrase

What is the substrate of that sucrase?

sucrose

What are the products of that sucrase?

glucose + fructose

What compound was used to immobilise the enzyme?

sodium alginate

What compound was used to harden the gel beads?

calcium chloride

Describe the procedure used to immobilise the enzyme?

• form a paste with the sodium alginate and water + leave for 5 mins to soak

• add yeast to water and leave for 5 mins

• mix the sodium alginate paste and yeast thoroughly

• dissolve calcium chloride in water in a large beaker

• syringe some of the mixture and slowly add drops into the calcium chloride solution

• allow the beads to harden for 15 minutes

Why are the beads rinsed before use?

to remove unbound enzyme/yeast cells

Describe how you applied the immobilised enzyme to convert the substrate to the product?

• pour beads into a separating funnel + yeast in water to another

• dissolve sucrose in warm water + add solution to separating funnel

• test the product by allowing it to drip onto a glucose testing strip

• record time for glucose to first form

What are the results of the immobilisation experiment?

• the immobilised enzymes are slower but have a clearer product

• the yeast water solution is quicker but has a cloudier product

Name an enzyme on which you investigated the effects of heat denaturation:

catalase (celery)

What is the substrate of catalase?

hydrogen peroxide

What is the product of hydrogen peroxide?

water and oxygen

Describe how you investigated the heat denaturation of the enzyme named:

• add 20cm³ pH buffer 9 solution

• add a drop of washing up liquid

• blend celery filter the solution into the graduated cylinder

• add hydrogen peroxide to another graduated cylinder

• place both in a 0^o, 25, 40, 60 water bath

• remove and add solutions together

• record foam volume after 2 minutes

• subtract original volume

ADP

Adenosine Diphosphate

• low energy carrier

ATP

Adenosine Triphosphate

• high energy carrier

Formation of ATP

ADP + P → ATP

• Anabolic reaction

Release of energy from ATP

ATP → ADP + P

• Catabolic reaction

ATP Cycle

NAD+

Nicotinamide Adenine Dinucleotide

• low energy carrier
• used in respiration

NADH

Nicotinamide Adenine Dinucleotide + Huydrogen

• high energy carrier

• used in respiration

Formation of NADH

NAD⁺ + 2e⁻ + H⁺ → NADH

• bonds with high energy electrons

Release of energy from NADH

NADH → NAD⁺ + 2e⁻ + H⁺

• releases high energy electrons

NADP+

Nicotinamide Adenine Dinucleotide Phosphate

• low energy carrier
• used in photosynthesis

NADPH

Nicotinamide Adenine Dinucleotide Phosphate + Hydrogen

• high energy carrier
• used in photosynthesis

NADH cycle