U1T2 - Enzymes Flashcards
What makes up your metabolism?
Chemical reactions which take place within our bodies.
What are the properties of enzymes?
Highly substrate specific, globular proteins, soluble, spherical, tertiary structure, fast acting. Affected by temp + pH.
What do enzymes have which allows them to catalyse reactions?
Highly substrate specific active site (substrate receptor site) which is complementary to a particular substrate.
When enzymes react and combine with the substrate, what do they form? What happens when the reaction is over?
Enzyme/substrate complex. Products are released and enzyme is left unchanged.
Enzymes are fast acting, what does this mean?
High turnover number. Convert many molecules of substrate per unit time.
What can enzymes build up and break down and how?
Molecules (carbs, proteins, lipids) hydrolysed by digestive enzymes. (starch + glycogen) built up from monomers for storage.
What type of protein are most enzymes? e.g. fibrous/conjugated etc.
Conjugated protein.
What is the non-protein part of a conjugated protein known as? What are the 2 types?
Cofactor. Prosthetic + coenzymes.
Give some examples of cofactors.
Metal ions (Mg2+, Ca2+, Fe2+).
How do cofactors work?
Form attachments to enzyme + change shape of active site, enabling a reaction to take place.
Give an example of a cofactor, its enzyme, and how it works.
Chloride ions for salivary amylase. Bind with amylase, change shape of active site slightly + makes it easier for enzyme-substrate complex to form.
Give examples of prosthetic groups.
Give examples of coenzymes.
Metal ions (zinc, iron, copper, haem group in catalase) Vitamins (NAD from vitamin B)
What do some coenzymes do?
Transfer chemical groups, atoms or electrons from one enzyme to another.
How is the activation energy overcome in many chemical reactions?
Heating of reactants, not possible for living organisms so we use enzymes instead.
As molecules react, what do they form? For how long? What is this known as?
High energy intermediates, momentarily (enzyme-substrate complex, ES) Transition state.
What is formed after the transition state? Why is it released?
Enzyme-product complex (EP) No longer fits active site.
How is activation energy lowered? What can do this?
Bringing substrate into correct orientation to facilitate bonding (breaking + making bonds) to form a product. Enzymes can do this.
Finish the equation…
E + S ->
ES -> EP -> E + P
What is the theory of enzyme action?
A molecules react they form enzyme-substrate complexes during the transition state which only happens if they have enough activation energy which is lowered by enzymes. An enzyme-product complex is then formed and because the products no longer fit the active site they are released
What environmental factors affect the rate of reaction of enzymes?
Temperature, pH, substrate concentration + enzyme concentration.
Describe how temperature affects the rate of reaction of enzymes up until the optimum temperature.
Increasing temp increases kinetic energy, meaning the molecules move around quicker and there are more collisions, resulting in more enzyme-substrate complexes being formed.
Describe how temperature affects the rate of reaction of enzymes above the optimum temperature.
An increase in temp will denature the enzyme. (60c) which is permanent + irreversible.
DO NOT MENTION TIME.
Describe how pH affects the rate of reaction of enzymes.
Each enzyme has an optimum pH where it works best. Changes in pH reduce enzyme activity. This is because the changes break ionic bonds to denature the enzyme eventually but this effect is reversible.
Describe how substrate concentration affects the rate of reaction of enzymes.
If enzyme conc is constant and substrate conc is increased, enzyme activity will gradually increase until a point as there are more substrates to fill the active sites. It will level off because all the active sites will become occupied so the enzyme concentration becomes the limiting factor.
Describe how enzyme concentration affects the rate of reaction of enzymes.
If substrate conc is constant + enzyme conc is increased, enzyme activity will gradually increase until a point as there are more active sites than there are substrate molecules so they become limiting. However, in living systems there is seldom substrate limiting.
Describe how product can affect the rate of reaction of enzymes.
Too much product can interfere with the active sites so blocking substrate from binding and reducing the reaction rate.
Give an example of non competitive inhibitor.
Cyanide non-reversible inhibitor of respiratory enzyme cytochrome oxidase.
How might you reduce the damage on someone who has had antifreeze?
Give them a massive dose of ethanol.
Why can enzymes be used as biomarkers?
Some enzymes are only present/active during a particular disease process.
Give an example of enzymes as biomarkers of disease. (respiratory)
White blood cells release elastase during respiratory infections. It hydrolyses elastin within alveolar walls leading to reduced lung function due to recoil function of lungs which is a part of exhalation. By detecting elastase in clinical sample (blood/urine/sputum) you can diagnose a respiratory infection which can then be treated.
