What is the overall role of enzymes?
They catalyse all the reaction in the body
What biomacromolecule are enzymes made from?
Proteins
Where can enzymes function in the body?
Inside and outside the cell
What is the substrate?
The substance which the enzyme acts upon
Are enzymes changed from the reaction?
No
What are the two things the enzyme may do to the substrate?
They may break complex substrate into two simpler products or they may join two simple substrates into one complex product
What is the active site?
The area of the enzyme within the cleft that the substrate binds to an where the reaction takes place
How many reactions does one enzyme catalyse?
One reaction only
What is the name for all the chemical reactions within the cell?
Metabolism
How many enzymes are there in the body?
Over 3000
How would a mutation affect an enzyme?
The enzyme would either, denature, change shape or have no affect
How would a cell vary their amount of enzymes?
They would either reduce or increase their rates of protein synthesis
How might rational drug design of enzymes help find a cure for cancer?
If they can create an enzyme that destroys tumor cells but not normal cells
What would happen if enzymes didn't exist?
Metabolism would be so slow that there would be insufficient energy to maintain life
Why are enzymes called biological catalysts?
Because they are made from the body and from living cells
What are intracellular enzymes?
Enzymes that catalyse reactions inside the cell
What are extracellular enzymes?
Enzymes that catalyse reactions outside the cell e.g. digestion
What are some digestive enzymes?
protease, lipase, pepsin, alpha amalase
What does protease break down?
Proteins
What does lipase break down?
Lipids
What does pepsin break down?
Breaks down proteins into peptides
What does alpha amalase break down?
It breaks down starch into glucose in the mouth
What does ATPase do?
It removes one of ATPs phosphate groups to release a large amount of energy. ATP gets broken down into ADP + phosphate
What does DNA polymerase do?
It tells the dna what direction to go in, ff DNA did not have a direction going from the 5 dash to 3 dash, the DNA could code for something completely different
What does ribonuclease breakdown?
RNA
What does catalase break down?
Breaks down hydrogen peroxide into oxygen and water
What are catabolic reactions?
They break down complex molecules into simpler ones, they involve the net release of energy, they are exergonic, the energy released goes to the ATP stores in the cell
What are examples of catabolic reactions?
Hydrolysis, cellular respiration
What are anabolic reactions?
They cause two substrate molecules to be drawn into the active site, chemical bonds are formed causing the two molecules to join and become a single molecule, they involve the net use of energy, they are endergonic
What are some examples of anabolic reactions?
Protein synthesis, photosynthesis
How does the substrate bind to the active site?
Through weak non-covalent bonds
What is activation energy?
The starting off energy that is needed for any reaction to take place
How do enzymes lower the activation energy?
Enzymes lower the activation energy by destabilizing bonds in the substrate so that it is more reactive, they lower the amount of energy needed for a reaction to take place
What is the induced fit model?
When the substrate does not exactly fit the shape of the active site so therefore the active site changes shape slightly and moulds around the substrate
What is the function of enzymes at low temperatures?
There is little rate of reaction
What are some factors that affect enzymes?
temperature, Ph, substrate concentration, enzyme concentration
What is an example of an enzyme that is only made of a protein?
pepsin
Are all enzymes made up of 100% protein?
No, some enzymes require a non-protein component to function
What is the protein part of an enzyme called?
The apoenzyme
What is the additional non-protein part of the enzyme called?
the cofactor
Cofactors may be organic molecules or inorganic ions - if they are organic they are called:
Coenzymes
What are permanently bound cofactors called?
prosthetic groups
What are temporarily attached cofactors called?
coenzymes
The active form of the enzyme when it has a cofactor attached is called the:
Holoenzyme
What do cofactors come in the form of?
minerals, vitamins and certain ions
How do cofactors help the enzyme?
Having a cofactor added helps alter the active site slightly and therefore makes it a better receptor for the substrate
What is an example of a cofactor?
Nickel in urease
What are competitive inhibitors?
They attach to the active site of the enzyme and block it so no other substrate can bind, in this way they are competing with the normal substrate
What are some examples of competitive inhibitors?
Poisons such as cyanide and arsenic
How can the affect of the competitive inhibitor be reduced?
by increasing the concentration of the substrate
What is a real life example of where a competitive inhibitor is used for health benefits?
When someone has poisoning from ethylene glycol they are given alcohol which acts as a competitive inhibitor. Ethylene glycol is not toxic in its form but when it is broken down by enzymes in the body it becomes very toxic. To stop the enzymes from breaki
What are non-competative inhibitors?
They bind to another site on the enzyme (the allosteric site) that is not the active site, this alters the shape of the enzyme and therefore changes the shape of the active site
What are some examples of non-competative inhibitors?
Heavy metals such as mercury and lead
Why do low temperatures reduce the rates of enzyme activity?
Because the enzymes and substrates are not moving around very fast meaning that there are not many collisions between them
Why does high temperature cause enzyme denaturation?
When the temperature gets too high it will cause enzyme stability to decrease and causes the active site to change its shape so the enzyme becomes denatured
What is the optimum temperature?
It is the temperature that the enzyme functions best at
what is the average optimum temperature for most human enzymes?
around 37 degrees Celsius
how do extreme ph levels affect the enzyme?
Changing Ph levels will alter the charge of the enzyme which will diminish the active site's ability to bind to the substrate
What are some Ph levels of some enzymes in the body?
Pepsin in the stomach has an optimum ph of 2, trypsin in the small intestine has an optimum ph of 8
What will happen if the substrate concentration is increased?
The enzyme activity will increase but will eventually plateau as the enzyme has reached its Vmax, the fasted rate it can work
What will happen if the enzyme concentration is increased?
The higher the concentration of the enzymes means a higher rate of reaction
The substrate binds to the enzyme forming what?
The enzyme substrate complex
All organisms that undergo aerobic respiration release what as a byproduct and therefore catalase is needed to break the hydrogen peroxide down?
hydrogen peroxide
enzyme
catalysts that speed up biological reactions, unchanged by the reaction. globular proteins, specific to their substrate, affected by temperature and pH. (Biological Catalyst)
active site
the position on the enzyme occupied by the subtrate. enzymes lower activation energy of reaction.
substrate specificity
enzyme specificity is due to complementary shape of the active site and subtrate. The active site is often composed of open loops of polar amino acids on the exterior of the enzyme molecule.
lock and key hypothesis
1 enzyme, 1 subtrate fits=product.
a) large globular protein enzyme
b) active site
c) subtrate which fits active site
d) activated complex
e) unchanged enzyme
f) product of reaction
effect of temperature on enzyme activity
As temperature increases, so does the rate of reaction up until the optimal temperature. After the optimal temperature, the rate of reaction decreases because the enzyme is denatured.
effect of pH on enzyme activity
All enzymes work best at optimal pH. above and below the optimal pH the rate of reaction decreases. Extreme pH changes can denature the enzyme.
substrate concentration
As the substrate concentration increases, so does the rate of reaction, until all of the active sites are bound and the rate of reaction levels off.
denaturation
___________ is the structural change in a protein that results in the loss (usually permanent) of its biological properties(temperature and pH)
Use of lactase in the production of lactose-free milk
lactose is a disacharide milk protein. Around 90% of all humans show some kind of lactose intolerance. People who are lactose intolerant can drink milk if its lactose free. Lactase is an enzyme extracted from a yeast that can digest the milk and protein t
enzyme immobolisation
It is possible to make the process more efficient by emmobolising the lactose on a recoverable surface such as alginate.
lactase
First, lactase is immobilized in alginate beads. Next the beads are placed in a container over which milk can be passed. milk is collected&recirculated to convert any remaining lactose to lucose and galactose. The circulation is maintained until all lacto
catabolic pathways
pathways breakdown molecules
anabolic pathways
pathways build up molecules
chain pathway
enzyme(1) is specific to substrate. This is changed to product.
ensyme(2) is spefic to product 1 which becomes the substrate and converted to product
enzyme(3) is specific to products which becomes the substrate and converted to product
product 3 is calle
cyclic pathway
The initial substrate is fed into the cycle.
enzyme (1) combines the regenerated 'intermediate 4' with initial substrate to catalyses the production of intermediate 1.
enzyme(2) is specific to intermediate 1 and converts intermediate 1 to intermediate 2.
induced-fit model
The lock and key hypothesis does not explain the broad specificity of some enzymes. Also, the molecular shape of active sites is not always complementary to that of the substrate. The induced-fit model attempts to overcome these difficulties.
Exergonic reactions
release more energy than the activation energy.
inhibitors
____________ are substances that reduce or completely stop the action of an enzyme. It can act on the active site(competitive) or on another region of the enzyme molecule(non competitive).
competitive
The substrate and inhibitor are chemically similar in molecular shpe. The inhibitor can bind to active site. The enzyme inhibitor complexing blocks subtrate from entering the active site. This blockage reduces the rate of reaction. at high concentrations
non-competitive inhibition
The substrate and inhibitor are chemically different. Inhibitor can't bind to active site. Inhibitor can bind to another region of the enzyme molecule. The bonding of the inhibiotr w/enzymes causes structural changes in the enzymemolecule. The active site
allosteric enzyme
_____________ has 2 binding sites: the active site and the allosteric site.
end-product inhibition with the allosteric enzyme
Isoleucine, the end product can inhibit the enzyme Thonine Deaminase. The inhibition occurs at an inhibition site on the enzyme but not the active site. An excess of end product switches off any more production of that product. As the end product is used
Catalysts
a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
Energy
the capacity to cause change/ do work
Chemical Energy
A form of potential energy that is stored in chemical bonds between atoms.
kinetic energy
energy of motion
potential energy
energy that matter possesses because of its location or structure
Photosynthesis is:
Endergonic
thermal energy
a type of kinetic energy associated with the random movement of atoms or molecules
Thermo dynamics
study of energy transformations
1st law of thermodynamics, First law of thermodynamics
A.K.A Law of energy conservations: Energy can be transferred and transformed but never created or destroyed.
Vmax
What is the maximum rate of product production at an enzyme concentration
Km
Substrate concentration at one half of the Vmax
What does Km measure/depend on
It measures enzyme affinity for a substrate and depends on the shape of enzyme and substrate
how does temperature affect enzyme activity?
a. as temperature increases, so does the rate of reaction because the molecules are moving faster and have a higher chance of hitting eachother b. at extremely high temperatures, the enzyme is denatured due to disruption of noncovalent bonds c. lower temp
how does pH affect enzyme activity?
a. changes shape of enzyme by interacting with noncovalent bonds b. also changes shape or charge properties of the substrate so that either the substrate cannot bind to the active site or it cannot undergo catalysis c. As pH increases, enzyme activity inc
how does salt concentration affect enzyme activity?
Depending on the case, salts can precipitate or unfold the enzyme. They can also interact with the active site and disrupt hydrogen binding and binding to ionic residues decreasing, or in some cases increasing, activity of the enzyme.
what is a noncompetitive inhibitor?
a. change the shape of the enzyme so it cannot bind to substrate
b. smaller Vmax, Km remains the same
what is a competitive inhibitor?
a. interfere with the active site of the enzyme so substrate cannot bind
b. reversible because binding is noncovalent
c. if enough substrate is added, it will outcompete the inhibitor and reach Vmax
d. Vmax remains the same, Km increases
what is an allosteric inhibitor?
a. binds to enzyme and changes shape of active site so substrate cannot bind and enzyme is turned off
b. binding through noncovalent interactions so are reversible
c. whether or not they bind to enzyme depends on concentration
d. the mechanism behind feed
what is an allosteric activator?
a. binds and puts active site in optimal configuration which favors substrate binding, higher efficiency
b. noncovalent, so reversible
c. also dependent on enzyme concentration
Active site
part of enzyme where substrate fits into
Random fact about hydrogen peroxide:
hydrogen peroxide is harmful to living things and it is broken by catalase
Random fact about Endergonic Reactions:
Endergonic Reactions require a net input of energy and yield products rich in potential energy.
Endothermic
Heat is being taken in (absorbed)
Endothermic pt2
Requires heat from surroundings, reactant will have less energy than products
activation energy
Amount of energy required to have a chemical reaction by stressing chemical bonds
Exothermic
Heat is being released
Entropy
Quantity of randomness or disorder
2nd law of thermodynamics, second law of thermodynamics
Energy transformations result in the universe becoming more disoriented
Random Fact
Reactions release an equal amount of energy to the difference of potential energy between reactants and products.
Fun fact about enzymes
they are reusable
Activation energy
The energy barrier that must be overcome before chemical reaction occurs
Fun fact about Activation energy:
Prevents molecules from breaking down
Fun fact about heat
Heat speeds up a reaction
Fun fact about enzymes pt2
Enzymes increase the rate of a reaction without being consumed by the reaction. Also btw enzymes lower activation energy
Fire diagram
Activation energy
Fire diagram pt2
Activation energy
Fire diagram pt3
Enzyme-substrate complex